stats

The amount of pyridoxine (in grams) in a multiple vitamin is normally distributed with mean 110 grams and standard deviation 25 grams. What is the probability that a randomly selected vitamin will contain between 82 and 100 grams of pyridoxine? Use four decimal places for your final answer.

.2132

The probability that the standard normal variable, Z, is more than -0.98 is _________. Use four decimal places for answer.

.8365

A recent survey indicated that the average amount spent for breakfast by business managers was $7.58 with a standard deviation of $0.42. It was felt that breakfasts on the West Coast were higher than $7.58. A sample of 81 business managers on the West Coast had an average breakfast cost of $7.65. Reference: Reference for the following two questions. Find the P-value for the test.

0.0668

A recent study shows that babies who are underweight at birth are 40% more likely to develop high blood pressure as adults. If 12 babies who were underweight at birth are selected at random, what is the probability that at most two of these babies will develop high blood pressure as adults?

0.083

A recent study of 750 internet users in Europe found that 35% of internet users were women. What is the 95% confidence interval of the true proportion of women in Europe who use the internet?

0.316<p<0.384

If the probability of a type II error in a hypothesis test is 0.45, and α =0.03, then the power of this test is

0.55

What is the 95% confidence interval for the standard deviation of birth weights at County General Hospital, if the standard deviation of the last 25 babies born there was 1.1 pounds?

0.9< α<1.5

A recent survey indicated that the average amount spent for breakfast by business managers was $7.58 with a standard deviation of $0.42. It was felt that breakfasts on the West Coast were higher than $7.58. A sample of 81 business managers on the West Coast had an average breakfast cost of $7.65. Reference: Reference for the following two questions. At α = 0.05, what is the critical value?

1.65

At a certain university, the average cost of books was $380 per student last semester and the population standard deviation was $75. This semester a sample of 40 students revealed an average cost of books of $400 per student. The Dean of Students believes that the costs are greater this semester. What is the test value for this hypothesis?

1.69

Using the z table, determine the critical value for the right-tailed test with α = 0.035.

1.81

A food snack manufacturer samples 13 bags of pretzels off the assembly line and weighs their contents. If the sample mean is 14.7 oz. and the sample standard deviation is 0.50 oz., find the 95% confidence interval of the true mean.

14.4<m<15.0

If the sample mean is 10, the hypothesized population mean is 6, and the population standard deviation is 2, compute the test value needed for the z test.

2.00

What is the critical value for a two-tailed t test when α = 0.02 and d.f. = 18?

2.552

For the data 15, 21, 28, 17, 19, 29, and 25, what is the mean?

22

A study of elephants is conducted to determine the average weight of a certain subspecies of elephants. The standard deviation for the population is 500 pounds. At a 80% level, how many elephants need to be weighed so the average weight will be accurate to within 350 pounds?

4

A lab technician is tested for her consistency by making multiple measurements of the cholesterol level in one blood sample. The target precision is a standard deviation of 1 mg/dL or less. If 12 measurements are taken and the standard deviation is 2 mg/dL, is there enough evidence to support the claim that her standard deviation is greater than the target, at α = .01?

Yes, since the χ2 test value 44.000 is greater than the critical value 24.725.

Sam Ying, a career counselor, claims the average number of years of schooling for an engineer is 15.8 years. A sample of 16 engineers had a mean of 15.0 years and a standard deviation of 1.5 years. The test value used in evaluating the claim would be -2.68.

False

Sandra Johnson, a researcher, believes her pulse rate will decrease with exercise. Her alternative hypothesis would contain an equal sign.

False

The amount of coffee consumed by an individual in a day is an example of a discrete numerical variable.

False

The number of hamburgers sold by Bob's Burgers would be an example of a qualitative variable.

False

The number of possible outcomes for the genders of the children a family of four children is 8.

False

The t-distribution has a variance that is less than one.

False

The lockers at a gymnasium have 4-digit combination locks. The first digit must be odd, the second digit (0 is considered an even number here) must be even, and the last 2 digits can be any number from 0 - 9, inclusive and repetitions are allowed. How many different possibilities are there?

2500

A statistician claims that the standard deviation of the weights of firemen is less than 25 pounds. A sample of 20 randomly chosen firemen had a standard deviation of their weights of 26.2 pounds. Assume the variable is normally distributed. At α = 0.05, what is the critical value χ2 for this test?

30.144

Using the following set of data: 60, 52, 48, 32, 62, 45, 48, 52, 60, and 48, what is the median?

50

A survey of 800 women shoppers found that 17% of them shop on impulse. What is the 98% confidence interval for the true proportion of women shoppers who shop on impulse?

True

Classify each of the following as nominal, ordinal, interval, or ratio data. The marital status of people in Las Vegas. The zip codes of alumni of State University. The outside temperature measured in Celsius. The rating score of Olympic ice skaters. The number of children per household. A. nominal B. ordinal C. interval D. ratio

The marital status of people in Las Vegas. Correct A. nominal The zip codes of alumni of State University. Correct A. nominal The outside temperature measured in Celsius. Correct C. interval The rating score of Olympic ice skaters. Correct B. ordinal The number of children per household. Correct D. ratio

Which of the following would be an appropriate null hypothesis?

The mean of a population is equal to 55.

Which of the following about the normal distribution is NOT true?

Theoretically, the mean, median and mode are the same.

The value that separates a rejection region from a nonrejection region is called the _____________.

critical value

Sampling distributions describe the distribution of

statistics.

Most likely in a right-skewed distribution

the median is less than the mean

The lockers at a gymnasium have 4-digit combination locks. The first digit must be odd, the second digit (0 is considered an even number here) must be even, and the last 2 digits can be any number from 0 - 9, inclusiveand repetitions are allowed. How many different possibilities are there?

the median is less than the mean

A Type II error is committed when

we don't reject a null hypothesis that is false

A Type II error is committed when

we don't reject a null hypothesis that is false.

A poll of 600 frequent business travelers found that 60% found business travel stimulating. What is tbe 95% confidence interval for the true proportion of business travelers who find business travel stimulating?

0.561 < p < 0.639

It was found that in a sample of 90 teenage boys, 70% of them have received speeding tickets. What is the 90% confidence interval of the true proportion of teenage boys who have received speeding tickets?

0.620<p<15.0

If we know that the length of time it takes a college student to find a parking spot in the library parking lot follows a normal distribution with a mean of 3.5 minutes and a standard deviation of 1 minute, find the probability that a randomly selected college student will find a parking spot in the library parking lot in less than 3 minutes.

0.7745

A recent survey indicated that a person living in the United States consumes approximately on average 99 pounds of beef per year with a standard deviation of 16.9 pounds. If a sample of 100 persons living in the U.S. is selected at random, what is the probability that the average beef consumption of this sample is between 97 and 101.5 pounds?

0.8116

The probability that house sales will increase in the next 6 months is estimated to be 0.25. The probability that the interest rates on housing loans will go up in the same period is estimated to be 0.74. The probability that house sales and interest rates will go up during the next 6 months is estimated to be 0.10. What is the probability that house sales or interest rates will increase during the next 6 months?

0.89

Using the standard normal distribution, what is P(Z > -1.64)?

0.9495

Classify each of the following as nominal, ordinal, interval, or ratio data. The marital status of people in Las Vegas. The zip codes of alumni of State University. The outside temperature measured in Celsius. The rating score of Olympic ice skaters. The number of children per household. A. nominal B. ordinal C. interval D. ratio

A. nominal The zip codes of alumni of State University. A. nominal The outside temperature measured in Celsius. C. interval The rating score of Olympic ice skaters. B. ordinal The number of children per household. D. ratio

The standard error of the mean

All of the above are true

The amount of time it takes to complete an examination has a skewed-left distribution with a mean of 65 minutes and a standard deviation of 8 minutes. If 64 students were randomly sampled, find the probability that the sample mean of the sampled students exceeds 71 minutes.

Approximately 0

A chi-square distribution is negatively skewed

False

A random sample of 100 stores from a large chain of 1,000 garden supply stores was selected to determine the average of lawnmowers sold at an end-of-season clearance sale. The sample results indicated an average of 6 and a standard deviation of 2 lawnmowers sold. A 95% confidence interval (5.623 to 6.377) was established based on these results. If the population had consisted of 10,000 stores, the confidence interval estimate of the mean would have been wider in range.

False

A random sample of 100 stores from a large chain of 1,000 garden supply stores was selected to determine the average of lawnmowers sold at an end-of-season clearance sale. The sample results indicated an average of 6 and a standard deviation of 2 lawnmowers sold. A 95% confidence interval (5.623 to 6.377) was established based on these results. Referring to the above statement, 95% of the stores have sold between 5.623 and 6.377 lawnmowers.

False

A researcher was using a t-distribution to find a 95% confidence interval. If the sample size was 18,the critical value used would be 2.101.

False

A retailer wants to extimate with 95% confidence the number of people who buy at his store. A previous study showed that 15% of those interviewed had shopped at his store. He wishes to be accurate within 3% of the true proportion. The minimum sample size necessary would be 943. True

False

A type I error is only a possibility when the null hypothesis is not rejected.

False

If 7 objects are taken three at a time, there would be 140 combinations.

False

Inferential statistics consists of generalizing from populations to samples.

False

A 95 % confidence interval is larger than a 90% confidence interval.

True

A club has 12 members. There are 1320 ways that a chairperson, a secretary, and a treasurer can be selected from these 12 members.

True

A confidence interval was constructed around a proportion. The interval was from 23.6% to 34.2%. The proportion that was used to construct this interval was 28.9%.

True

A random sample of 100 stores from a large chain of 1,000 garden supply stores was selected to determine the average of lawnmowers sold at an end-of-season clearance sale. The sample results indicated an average of 6 and a standard deviation of 2 lawnmowers sold. A 95% confidence interval (5.623 to 6.377) was established based on these results. Referring to the above scenario, of all possible samples of 100 stores taken from the population of 1,000 stores, 95% of the confidence intervals developed will contain the true population mean within the interval

True

A random sample of 100 stores from a large chain of 1,000 garden supply stores was selected to determine the average of lawnmowers sold at an end-of-season clearance sale. The sample results indicated an average of 6 and a standard deviation of 2 lawnmowers sold. A 95% confidence interval (5.623 to 6.377) was established based on these results. Referring to the above scenario, of all possible samples of 100 stores taken from the population of 1,000 stores, 95% of the confidence intervals developed will contain the true population mean within the interval.

True

A salesperson can travel from Los Angeles to Chicago by bus, plane, or car, and from Chicago to Cleveland by plane or car. Using a tree diagram, there would be 6 possible ways the salesperson can travel from Los Angeles to Cleveland.

True

If a sample has a mean of 10.5 and a variance of 11.5, the coefficient of variation would be 32.3%. True

True

In performing a hypothesis test, one should decide whether to reject or not reject the null hypothesis before summarizing the results.

True

One requirement for a probability distribution is that the sum of the probabilities of all the events in the sample space must equal one.

True

The confidence level of an interval estimate of a parameter is the probability that the interval estimate will contain the parameter.

True

The dean wants to estimate the average number of hours taken by students at Bison University. The standard deviation is thought to be 2.5 hours. If the dean wants to be 95% confident of finding the true mean within 1.5 hours, he must sample at least 11 students.

True

The power of a test measures the sensitivity of the test to detect a real difference in parameters if one actually exists.

True

The probability that a standard normal random variable, Z, is between -1.50 and 0.81 is 0.7242.

True

The t-distribution has a variance that is greater than one.

True

When the range of data is large, the data must be grouped into classes that are more than one unit in length.

True