stats chapter 10
The mean monthly electric bill for 4040 residents of the local apartment complex is $70$70. What is the best point estimate for the mean monthly electric bill for all residents of the local apartment complex?
$70
A biologist examines 2323 sedimentary samples for bromide concentration. The mean bromide concentration for the sample data is 0.3490.349 cc/cubic meter with a standard deviation of 0.05270.0527. Determine the 98%98% confidence interval for the population mean bromide concentration. Assume the population is approximately normal. Step 2 of 2 : Construct the 98%98% confidence interval. Round your answer to three decimal places.
( 0.3214 , 0.3766)
A sample of 55 strings of thread is randomly selected and the following thicknesses are measured in millimeters. Give a point estimate for the population standard deviation. Round your answer to three decimal places. 1.48,1.45,1.54,1.52,1.52
0.036 Standard Deviation, s: 0.036 (Sample). Standard Deviation, σ: 0.032 (Population).
A quality-conscious disk manufacturer wishes to know the fraction of disks his company makes which are defective. Step 1 of 2 : Suppose a sample of 322322 floppy disks is drawn. Of these disks, 306306 were not defective. Using the data, estimate the proportion of disks which are defective. Enter your answer as a fraction or a decimal number rounded to three decimal places.
0.050
A quality-conscious disk manufacturer wishes to know the fraction of disks his company makes which are defective. Step 1 of 2 : Suppose a sample of 425425 floppy disks is drawn. Of these disks, 3838 were defective. Using the data, estimate the proportion of disks which are defective. Enter your answer as a fraction or a decimal number rounded to three decimal places.
0.089
A quality-conscious disk manufacturer wishes to know the fraction of disks his company makes which are defective. Step 1 of 2 : Suppose a sample of 401401 floppy disks is drawn. Of these disks, 3636 were defective. Using the data, estimate the proportion of disks which are defective. Enter your answer as a fraction or a decimal number rounded to three decimal places.
0.090
A commercial farm uses a machine that packages corn in twenty-four ounce portions. A sample of 7878 packages of corn has a variance of 0.140.14. Construct the 90%90% confidence interval to estimate the variance of the weights of the packages prepared by the machine. Round your answers to two decimal places.
0.11 0.19
A quality-conscious disk manufacturer wishes to know the fraction of disks his company makes which are defective. Step 1 of 2 : Suppose a sample of 23462346 floppy disks is drawn. Of these disks, 19711971 were not defective. Using the data, estimate the proportion of disks which are defective. Enter your answer as a fraction or a decimal number rounded to three decimal places.
0.160
An environmentalist wants to find out the fraction of oil tankers that have spills each month. Step 1 of 2 : Suppose a sample of 432432 tankers is drawn. Of these ships, 337337 did not have spills. Using the data, estimate the proportion of oil tankers that had spills. Enter your answer as a fraction or a decimal number rounded to three decimal places.
0.22
An environmentalist wants to find out the fraction of oil tankers that have spills each month. Step 1 of 2 : Suppose a sample of 333333 tankers is drawn. Of these ships, 257257 did not have spills. Using the data, estimate the proportion of oil tankers that had spills. Enter your answer as a fraction or a decimal number rounded to three decimal places.
0.228
he state education commission wants to estimate the fraction of tenth grade students that have reading skills at or below the eighth grade level. Step 1 of 2 : Suppose a sample of 369369 tenth graders is drawn. Of the students sampled, 285285 read above the eighth grade level. Using the data, estimate the proportion of tenth graders reading at or below the eighth grade level. Enter your answer as a fraction or a decimal number rounded to three decimal places.
0.228
The state education commission wants to estimate the fraction of tenth grade students that have reading skills at or below the eighth grade level. Step 1 of 2 : Suppose a sample of 24042404 tenth graders is drawn. Of the students sampled, 18031803 read above the eighth grade level. Using the data, estimate the proportion of tenth graders reading at or below the eighth grade level. Enter your answer as a fraction or a decimal number rounded to three decimal places.
0.250
An automotive manufacturer wants to know the proportion of new car buyers who prefer foreign cars over domestic. Step 1 of 2 : Suppose a sample of 13131313 new car buyers is drawn. Of those sampled, 341341 preferred foreign over domestic cars. Using the data, estimate the proportion of new car buyers who prefer foreign cars. Enter your answer as a fraction or a decimal number rounded to three decimal places.
0.260
The American Heart Association is about to conduct an anti-smoking campaign and wants to know the fraction of Americans over 2121 who smoke. Step 1 of 2 : Suppose a sample of 383383 Americans over 2121 is drawn. Of these people, 280280 don't smoke. Using the data, estimate the proportion of Americans over 2121who smoke. Enter your answer as a fraction or a decimal number rounded to three decimal places.
0.269
The FBI wants to determine the effectiveness of their 1010 Most Wanted list. To do so, they need to find out the fraction of people who appear on the list that are actually caught. Step 1 of 2 : Suppose a sample of 531531 suspected criminals is drawn. Of these people, 148148 were captured. Using the data, estimate the proportion of people who were caught after being on the 1010 Most Wanted list. Enter your answer as a fraction or a decimal number rounded to three decimal places.
0.279
The American Heart Association is about to conduct an anti-smoking campaign and wants to know the fraction of Americans over 2626 who smoke. Step 1 of 2 : Suppose a sample of 897897 Americans over 2626 is drawn. Of these people, 637637 don't smoke. Using the data, estimate the proportion of Americans over 2626 who smoke. Enter your answer as a fraction or a decimal number rounded to three decimal places.
0.2898
An automotive manufacturer wants to know the proportion of new car buyers who prefer foreign cars over domestic. Step 1 of 2 : Suppose a sample of 24762476 new car buyers is drawn. Of those sampled, 742742 preferred foreign over domestic cars. Using the data, estimate the proportion of new car buyers who prefer foreign cars. Enter your answer as a fraction or a decimal number rounded to three decimal places.
0.300
The FBI wants to determine the effectiveness of their 1010 Most Wanted list. To do so, they need to find out the fraction of people who appear on the list that are actually caught. Step 1 of 2 : Suppose a sample of 514514 suspected criminals is drawn. Of these people, 164164 were captured. Using the data, estimate the proportion of people who were caught after being on the 1010 Most Wanted list. Enter your answer as a fraction or a decimal number rounded to three decimal places.
0.319
A commercial farm uses a machine that packages blueberries in twelve ounce portions. A sample of 100100 packages of blueberries has a standard deviation of 0.410.41. Construct the 98%98% confidence interval to estimate the standard deviation of the weights of the packages prepared by the machine. Round your answers to two decimal places.
0.35 0.49
proportion
1. The relationship of one thing to another in size, amount, etc. 2. Size or weight relationships among structures or among elements in a single structure. The symbol p indicates the proportion in the population that possess the given attribute and pˆp^ is the proportion in the sample that possess the attribute. Since pˆp^ is computed from a random sample, pˆp^ is a random variable whose value depends on which random sample is selected.
Consider a sample of golf balls. Their diameters are measured and found to have a standard deviation of 1.11. Give a point estimate for the population standard deviation in diameters of golf balls. Round your answer to two decimal places, if necessary.
1.11
In a sample of 2020 jars of strawberry jelly, the average weight was found to be 22.8oz22.8oz with a variance of 1.21.2. Give a point estimate for the population variance of the weight of the jars of strawberry jelly. Round your answer to two decimal places, if necessary
1.2
A consumer affairs investigator records the repair cost for 2323 randomly selected refrigerators. A sample mean of $88.05$88.05 and standard deviation of $10.52$10.52 are subsequently computed. Determine the 80%80% confidence interval for the mean repair cost for the refrigerators. Assume the population is approximately normal. Step 1 of 2 : Find the critical value that should be used in constructing the confidence interval. Round your answer to three decimal places
1.321
A geologist examines 1717 sedimentary samples for magnesium concentration. The mean magnesium concentration for the sample data is 0.4880.488 cc/cubic meter with a standard deviation of 0.04180.0418. Determine the 80%80% confidence interval for the population mean magnesium concentration. Assume the population is approximately normal. Step 1 of 2 : Find the critical value that should be used in constructing the confidence interval. Round your answer to three decimal places.
1.337
Noise levels at 66 airports were measured in decibels yielding the following data: 137,132,145,152,209,169137,132,145,152,209,169 Construct the 80%80% confidence interval for the mean noise level at such locations. Assume the population is approximately normal. Copy Data Step 3 of 4 : Find the critical value that should be used in constructing the confidence interval. Round your answer to three decimal places.
1.476
Noise levels at 66 manufacturing plants were measured in decibels yielding the following data: 147,144,146,127,154,140147,144,146,127,154,140 Construct the 80%80% confidence interval for the mean noise level at such locations. Assume the population is approximately normal. Copy Data Step 3 of 4 : Find the critical value that should be used in constructing the confidence interval. Round your answer to three decimal places
1.476
A consumer affairs investigator records the repair cost for 2020 randomly selected refrigerators. A sample mean of $57.22$57.22 and standard deviation of $25.76$25.76 are subsequently computed. Determine the 90%90% confidence interval for the mean repair cost for the refrigerators. Assume the population is approximately normal. Step 1 of 2 : Find the critical value that should be used in constructing the confidence interval. Round your answer to three decimal places
1.729
A certain test preparation course is designed to help students improve their scores on the LSAT exam. A mock exam is given at the beginning and end of the course to determine the effectiveness of the course. The following measurements are the net change in 33 students' scores on the exam after completing the course: −6,11,18−6,11,18 Using these data, construct a 90%90% confidence interval for the average net change in a student's score after completing the course. Assume the population is approximately normal. Copy Data Step 2 of 4 : Calculate the sample standard deviation for the given sample data. Round your answer to one decimal place
12.3
A certain test preparation course is designed to help students improve their scores on the USMLE exam. A mock exam is given at the beginning and end of the course to determine the effectiveness of the course. The following measurements are the net change in 33 students' scores on the exam after completing the course: 15,20,1815,20,18 Using these data, construct a 90%90% confidence interval for the average net change in a student's score after completing the course. Assume the population is approximately normal. Copy Data Step 4 of 4 : Construct the 90%90% confidence interval. Round your answer to one decimal place.
13.5 21.9
Noise levels at 66 manufacturing plants were measured in decibels yielding the following data: 147,144,146,127,154,140147,144,146,127,154,140 Construct the 80%80% confidence interval for the mean noise level at such locations. Assume the population is approximately normal. Copy Data Step 4 of 4 : Construct the 80%80% confidence interval. Round your answer to one decimal place.
137.53 148.47
At the local college, a study found that students earned an average of 14.414.4 credit hours per semester. A sample of 117117 students was taken. What is the best point estimate for the average number of credit hours per semester for all students at the local college?
14.4
Noise levels at 66 manufacturing plants were measured in decibels yielding the following data: 147,144,146,127,154,140 Construct the 80%80% confidence interval for the mean noise level at such locations. Assume the population is approximately normal. Copy Data Step 1 of 4 : Calculate the sample mean for the given sample data. Round your answer to one decimal place.
143
What is the best point estimate for the population's variance if the sample standard deviation is 15.915.9? Round your answer to one decimal place, if necessary.
15.9^2= 252.8
Noise levels at 66 airports were measured in decibels yielding the following data: 137,132,145,152,209,169137,132,145,152,209,169 Construct the 80%80% confidence interval for the mean noise level at such locations. Assume the population is approximately normal. Copy Data Step 1 of 4 : Calculate the sample mean for the given sample data. Round your answer to one decimal place.
157.3
A market research company wishes to know how many energy drinks adults drink each week. They want to construct a 85%85% confidence interval with an error of no more than 0.080.08. A consultant has informed them that a previous study found the mean to be 7.77.7 energy drinks per week and found the standard deviation to be 0.70.7. What is the minimum sample size required to create the specified confidence interval? Round your answer up to the next integer.
159
Determine the critical values for the confidence interval for the population variance from the given values. Round your answers to three decimal places. n=30n=30 and α=0.05α=0.05.
16.047 45.722
Determine the critical values for the confidence interval for the population standard deviation from the given values. Round your answers to three decimal places. n=7n=7 and c=0.98c=0.98.
16.812 0.872
A certain test preparation course is designed to help students improve their scores on the LSAT exam. A mock exam is given at the beginning and end of the course to determine the effectiveness of the course. The following measurements are the net change in 66 students' scores on the exam after completing the course: 23,18,23,12,13,2323,18,23,12,13,23 Using these data, construct a 80%80% confidence interval for the average net change in a student's score after completing the course. Assume the population is approximately normal. Copy Data Step 1 of 4 : Calculate the sample mean for the given sample data. Round your answer to one decimal place.
18.7
A certain test preparation course is designed to help students improve their scores on the LSAT exam. A mock exam is given at the beginning and end of the course to determine the effectiveness of the course. The following measurements are the net change in 55 students' scores on the exam after completing the course: 20,26,20,11,1920,26,20,11,19 Using these data, construct a 90%90% confidence interval for the average net change in a student's score after completing the course. Assume the population is approximately normal. Copy Data Step 1 of 4 : Calculate the sample mean for the given sample data. Round your answer to one decimal place.
19.2
At the local college, a study found that students had an average of 2.12.1 roommates per semester. A sample of 100100 students was taken. What is the best point estimate for the average number of roommates per semester for all students at the local college?
2.1
A biologist examines 2323 sedimentary samples for bromide concentration. The mean bromide concentration for the sample data is 0.3490.349 cc/cubic meter with a standard deviation of 0.05270.0527. Determine the 98%98% confidence interval for the population mean bromide concentration. Assume the population is approximately normal. Step 1 of 2 : Find the critical value that should be used in constructing the confidence interval. Round your answer to three decimal places.
2.508
Consider a sample of rubber bands. Their weights are measured and found to have a variance o 2.57. Give a point estimate for the population variance in weights of rubber bands. Round your answer to two decimal places, if necessary.
2.57
In a sample of 34 full size down comforters, the average weight was found to be 34.5oz with a variance of 2.6. Give a point estimate for the population variance of the weight of the full size down comforters. Round your answer to two decimal places, if necessary
2.60
A marketing research company desires to know the mean consumption of meat per week among males over age 4242. A sample of 324324 males over age 4242 was drawn and the mean meat consumption was 33 pounds. Assume that the population standard deviation is known to be 11 pounds. Construct the 85%85% confidence interval for the mean consumption of meat among males over age 4242. Round your answers to one decimal place.
2.9 3.1
A certain test preparation course is designed to help students improve their scores on the USMLE exam. A mock exam is given at the beginning and end of the course to determine the effectiveness of the course. The following measurements are the net change in 33 students' scores on the exam after completing the course: 15,20,1815,20,18 Using these data, construct a 90%90% confidence interval for the average net change in a student's score after completing the course. Assume the population is approximately normal. Copy Data Step 3 of 4 : Find the critical value that should be used in constructing the confidence interval. Round your answer to three decimal places
2.920
An economist wants to estimate the mean per capita income (in thousands of dollars) for a major city in California. He believes that the mean income is $22$22, and the standard deviation is known to be $8.4$8.4. How large of a sample would be required in order to estimate the mean per capita income at the 99%99% level of confidence with an error of at most $0.48$0.48? Round your answer up to the next integer.
2033
An economist wants to estimate the mean per capita income (in thousands of dollars) for a major city in Texas. Suppose that the mean income is found to be $23.1$23.1 for a random sample of 12561256 people. Assume the population standard deviation is known to be $6$6. Construct the 90%90% confidence interval for the mean per capita income in thousands of dollars. Round your answers to one decimal place.
22.8 23.4
An economist wants to estimate the mean per capita income (in thousands of dollars) for a major city in Texas. Suppose that the mean income is found to be $23.5$23.5 for a random sample of 327327 people. Assume the population standard deviation is known to be $8.7$8.7. Construct the 80%80% confidence interval for the mean per capita income in thousands of dollars. Round your answers to one decimal place
22.9 24.1
The state education commission wants to estimate the fraction of tenth grade students that have reading skills at or below the eighth grade level. In an earlier study, the population proportion was estimated to be 0.170.17. How large a sample would be required in order to estimate the fraction of tenth graders reading at or below the eighth grade level at the 80%80% confidence level with an error of at most 0.030.03? Round your answer up to the next integer.
258
Noise levels at 66 airports were measured in decibels yielding the following data: 137,132,145,152,209,169137,132,145,152,209,169 Construct the 80%80% confidence interval for the mean noise level at such locations. Assume the population is approximately normal. Copy Data Step 2 of 4 : Calculate the sample standard deviation for the given sample data. Round your answer to one decimal place.
28.4
At the local college, a study found that students completed an average of 3.43.4 classes per semester. A sample of 128128 students was taken. What is the best point estimate for the average number of classes per semester for all students at the local college?
3.4
What is the best point estimate for the population's standard deviation if the sample standard deviation is 36.836.8? Round your answer to one decimal place, if necessary.
36.8
What is the best point estimate for the population's standard deviation if the sample standard deviation is 36.8? Round your answer to one decimal place, if necessary.
36.8
A fast food restaurant executive wishes to know how many fast food meals adults eat each week. They want to construct a 99%99% confidence interval with an error of no more than 0.060.06. A consultant has informed them that a previous study found the mean to be 7.57.5 fast food meals per week and found the standard deviation to be 1.41.4. What is the minimum sample size required to create the specified confidence interval? Round your answer up to the next integer
3625
The weights of 9191 randomly selected mattresses were found to have a standard deviation of 4.734.73. Construct the 95%95% confidence interval for the population standard deviation of the weights of all mattresses in this factory. Round your answers to two decimal places.
4.13 5.54
The mean monthly car payment for 6161 residents of the local apartment complex is $546$546. What is the best point estimate for the mean monthly car payment for all residents of the local apartment complex?
546
NASA is conducting an experiment to find out the fraction of people who black out at G forces greater than 66. In an earlier study, the population proportion was estimated to be 0.40.4. How large a sample would be required in order to estimate the fraction of people who black out at 66 or more Gs at the 95%95% confidence level with an error of at most 0.040.04? Round your answer up to the next integer.
577
What is the best point estimate for the population's variance if the sample standard deviation is 25.625.6? Round your answer to one decimal place, if necessary.
655.36
The mean monthly electric bill for 49 residents of the local apartment complex is $68. What is the best point estimate for the mean monthly electric bill for all residents of the local apartment complex?
68
The mean monthly electric bill for 4040 residents of the local apartment complex is $70$70. What is the best point estimate for the mean monthly electric bill for all residents of the local apartment complex?
70
An economist wants to estimate the mean per capita income (in thousands of dollars) for a major city in Texas. He believes that the mean income is $31.3$31.3, and the standard deviation is known to be $9.4$9.4. How large of a sample would be required in order to estimate the mean per capita income at the 85%85% level of confidence with an error of at most $0.46$0.46? Round your answer up to the next integer.
866
Noise levels at 66 manufacturing plants were measured in decibels yielding the following data: 147,144,146,127,154,140 Construct the 80%80% confidence interval for the mean noise level at such locations. Assume the population is approximately normal. Copy Data Step 2 of 4 : Calculate the sample standard deviation for the given sample data. Round your answer to one decimal place
9.0774
NASA is conducting an experiment to find out the fraction of people who black out at G forces greater than 66. In an earlier study, the population proportion was estimated to be 0.370.37. How large a sample would be required in order to estimate the fraction of people who black out at 66 or more Gs at the 99%99% confidence level with an error of at most 0.040.04? Round your answer up to the next integer.
967
The state education commission wants to estimate the fraction of tenth grade students that have reading skills at or below the eighth grade level. In an earlier study, the population proportion was estimated to be 0.180.18. How large a sample would be required in order to estimate the fraction of tenth graders reading at or below the eighth grade level at the 90%90% confidence level with an error of at most 0.020.02? Round your answer up to the next integer.
999
Construct the confidence interval for the population standard deviation for the given values. Round your answers to one decimal place. n=20n=20, s=4.2s=4.2, and c=0.99
=(2.947,6.998)
Mean Squared Error (MSE)
An estimator's average squared distance from the true parameter is referred to as its mean squared error (MSE). The mean squared error for the sample mean is given by
Determine the critical values for the confidence interval for the population standard deviation from the given values. Round your answers to three decimal places. n=19n=19 and c=0.8c=0.8.
Degree of freedom = n - 1 = 19 - 1 = 18 10.865 by using chi square critical value table or by using Excel command =CHIINV(1-(0.2/2),18) 25.898 by using chi square critical value table or by using Excel command =CHIINV((0.2/2),18)
Desired Accuracy
In order to assure the desired level of confidence, always round the value obtained for the sample size up to the next integer
Noise levels at 66 airports were measured in decibels yielding the following data: 137,132,145,152,209,169137,132,145,152,209,169 Construct the 80%80% confidence interval for the mean noise level at such locations. Assume the population is approximately normal. Copy Data Step 4 of 4 : Construct the 80%80% confidence interval. Round your answer to one decimal place.
L 140.2 H 174.4
The water works commission needs to know the mean household usage of water by the residents of a small town in gallons per day. Assume that the population standard deviation is 1.51.5 gallons. The mean water usage per family was found to be 16.216.2 gallons per day for a sample of 179179 families. Construct the 85%85% confidence interval for the mean usage of water. Round your answers to one decimal place.
L 16 H 16.4
A marketing research company desires to know the mean consumption of milk per week among males over age 2525. A sample of 22132213 males over age 2525 was drawn and the mean milk consumption was 2.42.4 liters. Assume that the population standard deviation is known to be 1.21.2 liters. Construct the 95%95% confidence interval for the mean consumption of milk among males over age 2525. Round your answers to one decimal place.
L 2.35 H 2.45
A consumer affairs investigator records the repair cost for 2020 randomly selected refrigerators. A sample mean of $57.22$57.22 and standard deviation of $25.76$25.76 are subsequently computed. Determine the 90%90% confidence interval for the mean repair cost for the refrigerators. Assume the population is approximately normal. Step 2 of 2 : Construct the 90%90% confidence interval. Round your answer to two decimal places.
L 49.26 H
A supervisor records the repair cost for 1717 randomly selected TVs. A sample mean of $94.57$94.57 and standard deviation of $20.65$20.65 are subsequently computed. Determine the 80%80% confidence interval for the mean repair cost for the TVs. Assume the population is approximately normal. Step 2 of 2 : Construct the 80%80% confidence interval. Round your answer to two decimal places.
L 87.88 H 101.27
A quality-conscious disk manufacturer wishes to know the fraction of disks his company makes which are defective. Step 2 of 2 : Suppose a sample of 322322 floppy disks is drawn. Of these disks, 306306 were not defective. Using the data, construct the 90%90% confidence interval for the population proportion of disks which are defective. Round your answers to three decimal places.
LL 0.030 UL 0.070
A quality-conscious disk manufacturer wishes to know the fraction of disks his company makes which are defective. Step 2 of 2 : Suppose a sample of 425425 floppy disks is drawn. Of these disks, 3838 were defective. Using the data, construct the 85%85% confidence interval for the population proportion of disks which are defective. Round your answers to three decimal places.
LL 0.069 UL 0.109
A quality-conscious disk manufacturer wishes to know the fraction of disks his company makes which are defective. Step 2 of 2 : Suppose a sample of 23462346 floppy disks is drawn. Of these disks, 19711971 were not defective. Using the data, construct the 85%85% confidence interval for the population proportion of disks which are defective. Round your answers to three decimal places.
LL 0.149 UL 0.171
An environmentalist wants to find out the fraction of oil tankers that have spills each month. Step 2 of 2 : Suppose a sample of 563563 tankers is drawn. Of these ships, 445445 did not have spills. Using the data, construct the 98%98% confidence interval for the population proportion of oil tankers that have spills each month. Round your answers to three decimal places.
LL 0.170 UL 0.250
An environmentalist wants to find out the fraction of oil tankers that have spills each month. Step 2 of 2 : Suppose a sample of 432432 tankers is drawn. Of these ships, 337337 did not have spills. Using the data, construct the 85%85%confidence interval for the population proportion of oil tankers that have spills each month. Round your answers to three decimal places
LL 0.191 UL 0.249
The state education commission wants to estimate the fraction of tenth grade students that have reading skills at or below the eighth grade level. Step 2 of 2 : Suppose a sample of 369369 tenth graders is drawn. Of the students sampled, 285285 read above the eighth grade level. Using the data, construct the 85%85%confidence interval for the population proportion of tenth graders reading at or below the eighth grade level. Round your answers to three decimal places
LL 0.196 UP 0.259
The American Heart Association is about to conduct an anti-smoking campaign and wants to know the fraction of Americans over 2121 who smoke. Step 2 of 2 : Suppose a sample of 383383 Americans over 2121 is drawn. Of these people, 280280 don't smoke. Using the data, construct the 80%80% confidence interval for the population proportion of Americans over 2121 who smoke. Round your answers to three decimal places.
LL 0.240 UL 0.298
The FBI wants to determine the effectiveness of their 1010 Most Wanted list. To do so, they need to find out the fraction of people who appear on the list that are actually caught. Step 2 of 2 : Suppose a sample of 531531 suspected criminals is drawn. Of these people, 148148 were captured. Using the data, construct the 95%95% confidence interval for the population proportion of people who are captured after appearing on the 1010 Most Wanted list. Round your answers to three decimal places.
LL 0.241 UL0..317
The American Heart Association is about to conduct an anti-smoking campaign and wants to know the fraction of Americans over 2626 who smoke. Step 2 of 2 : Suppose a sample of 897897 Americans over 2626 is drawn. Of these people, 637637 don't smoke. Using the data, construct the 95%95% confidence interval for the population proportion of Americans over 2626 who smoke. Round your answers to three decimal places.
LL 0.260 UL 0.320
The FBI wants to determine the effectiveness of their 1010 Most Wanted list. To do so, they need to find out the fraction of people who appear on the list that are actually caught. Step 2 of 2 : Suppose a sample of 278278 suspected criminals is drawn. Of these people, 8888 were captured. Using the data, construct the 85%85% confidence interval for the population proportion of people who are captured after appearing on the 1010 Most Wanted list. Round your answers to three decimal places.
LL 0.277 UL 0.357
An automotive manufacturer wants to know the proportion of new car buyers who prefer foreign cars over domestic. Step 2 of 2 : Suppose a sample of 24762476 new car buyers is drawn. Of those sampled, 742742 preferred foreign over domestic cars. Using the data, construct the 98%98% confidence interval for the population proportion of new car buyers who prefer foreign cars over domestic cars. Round your answers to three decimal places.
LL 0.279 UL 0.322
Construct the confidence interval for the population variance for the given values. Round your answers to one decimal place. n=13n=13, s2=9.4s2=9.4, and c=0.98
Lower confidence limit for population variance= 4.3 Upper confidence limit for population variance =31.6
A geologist examines 1717 sedimentary samples for magnesium concentration. The mean magnesium concentration for the sample data is 0.4880.488 cc/cubic meter with a standard deviation of 0.04180.0418. Determine the 80%80% confidence interval for the population mean magnesium concentration. Assume the population is approximately normal. Step 2 of 2 : Construct the 80%80% confidence interval. Round your answer to three decimal places.
Lower confidence limit=0.4744 Upper confidence limit=0.5016
The water works commission needs to know the mean household usage of water by the residents of a small town in gallons per day. Assume that the population standard deviation is 1.71.7 gallons. The mean water usage per family was found to be 15.815.8 gallons per day for a sample of 249249 families. Construct the 80%80% confidence interval for the mean usage of water. Round your answers to one decimal place.
Lower endpoint = 15.7 Upper endpoint = 15.9
A quality-conscious disk manufacturer wishes to know the fraction of disks his company makes which are defective. Step 2 of 2 : Suppose a sample of 12211221 floppy disks is drawn. Of these disks, 6161 were defective. Using the data, construct the 99%99% confidence interval for the population proportion of disks which are defective. Round your answers to three decimal places.
Lower limit for confidence interval=0.034 Upper limit for confidence interval=0.066
The state education commission wants to estimate the fraction of tenth grade students that have reading skills at or below the eighth grade level. Step 2 of 2 : Suppose a sample of 24042404 tenth graders is drawn. Of the students sampled, 18031803 read above the eighth grade level. Using the data, construct the 98%98% confidence interval for the population proportion of tenth graders reading at or below the eighth grade level. Round your answers to three decimal places.
Lower limit for confidence interval=0.229 Upper limit for confidence interval=0.271
statistical inference
Using properly drawn sample data to draw conclusions about the population is called
maximum error
in estimating μ using the point estimate x⎯⎯x_ with a specified level of confidence. The maximum error of estimation is also referred to as the margin of error, E
estimator
is a strategy or rule that is used to estimate a population parameter. If the rule is applied to a specific set of data, the result is an estimate
interval estimator
is made by developing an upper and lower boundary for an interval that will hopefully contain the population parameter.
confidence interval
is used to describe the method of construction rather than a particular interval
The following sample of lengths was taken from 88 nails off the assembly line. Construct the 95%95% confidence interval for the population variance for all nails that come off the assembly line. Round your answers to two decimal places. 13.9,14.2,13.4,13.5,13.6,13.7,13.4,13.7
ll 0.03 UL 0.30
An automotive manufacturer wants to know the proportion of new car buyers who prefer foreign cars over domestic. Step 2 of 2 : Suppose a sample of 13131313 new car buyers is drawn. Of those sampled, 341341 preferred foreign over domestic cars. Using the data, construct the 98%98%confidence interval for the population proportion of new car buyers who prefer foreign cars over domestic cars. Round your answers to three decimal places.
lower endpoint = 0.232 upper endpoint = 0.288
degrees of freedom
n-1 for any t-distribution are computed in the following manner.
A consumer affairs investigator records the repair cost for 2323 randomly selected refrigerators. A sample mean of $88.05$88.05 and standard deviation of $10.52$10.52 are subsequently computed. Determine the 80%80% confidence interval for the mean repair cost for the refrigerators. Assume the population is approximately normal. Step 2 of 2 : Construct the 80%80% confidence interval. Round your answer to two decimal places.
where , Lower limit : 85.152 Upper limit : 90.948
