STATS FINAL
A government agency was charged by the legislature with estimating the length of time it takes citizens to fill out various forms. The agency generated an 85% confidence interval, a 90% confidence interval, and a 99% confidence interval, all of which are listed below. Which one is the 85% confidence interval?
(12.63, 12.97)
Cell phone bills for a city's residents have a mean of $64 and a standard deviation of $14. Random samples of 100 bills are drawn from this population, and the mean of each sample is found. What is the sampling error of the mean?
1.4
The average sales price of single-family houses in Charlotte is $350,000 with a standard deviation of $40,000. A random sample of 100 single-family houses in Charlotte is selected. Let �¯ represent the mean sales price of the sample. What is the mean of the sampling distribution?
350,000
Cell phone bills for a city's residents have a mean of $64 and a standard deviation of $14. Random samples of 100 bills are drawn from this population, and the mean of each sample is found. What is the mean of the sampling distribution?
64
If every else remain the same which of the following confidence level will result the widest confidence interval?
99%
You are taking a multiple-choice quiz that consists of five questions. Each question had four possible answers, only one of which is correct. To complete the quiz, you randomly guess the answer to each question. Which of the following shows the correct excel formula to compute the probability of guessing at least four answers correctly?
=1 - BINOM.DIST(3, 5, 0.25, TRUE)
A survey shows that people use cell phones an average of 1.6 years with a standard deviation of 0.3 years. A user is randomly selected. If cell phone use is normally distributed, we can use Excel to calculate the probability that the randomly selected user uses their phone for more than 1 year with the function:
=1 - NORM.DIST(1, 1.6, 0.3, TRUE)
A survey shows that people use cell phones for an average of 1.6 years with a standard deviation of 0.3 years. A user is randomly selected. If cell phone use is normally distributed, we can use Excel to calculate the probability that the randomly selected user uses their phone for more than 1 year with the function:
=1 - NORM.DIST(1, 1.6, 0.3, TRUE)
Given a T distribution with the degrees of freedom of 16. Which function finds the probability that T is greater than 1.4?
=1-T.DIST(1.4, 16, TRUE)
How would you find the mean of data in the range B1 to B10 in Excel?
=AVERAGE(B1:B10)
A survey shows that people use cell phones for an average of 1.6 years with a standard deviation of 0.3 years. A user is randomly selected. If cell phone use is normally distributed, we can use Excel to calculate the probability that the randomly selected user uses their phone for less than 1 year with the function:
=NORM.DIST(1, 1.6, 0.3, TRUE)
A randomly selected sample of size 17 is taken. Assume the population is normally distributed. Which function finds the probability that t is less than 1.4?
=T.DIST(1.4, 16, TRUE)
In a situation of hypothesis testing, what happens when the null hypothesis �0 is wrongly rejected when it is actually true?
A Type I error occurs
The score made by a particular student on a national standardized exam is the 75th percentile. This means that
About 75% of all scores on the exam were equal to or less than his
The score made by a particular student on a national standardized exam is the 75th percentile. This means that
About 75% of all scores on the exam were lower than his.
There were 1000 students who took part in the common final exam on STAT 1222. The average is 70 with a standard deviation 8. If a student got a z-score of 3.10 in this exam, which of the following is true?
Compared with other students in this exam, this student did extremely well.
Which of the following statements are true about the sampling distribution of �¯? I. The mean of the sampling distribution is equal to the mean of the population. II. The standard deviation of the sampling distribution is equal to the standard deviation of the population. III. The shape of the sampling distribution is always approximately normal.
I only
Seven bear tracks were found in the woods. Their length was measured in inches and recorded in the table below: If another bear track was found that was 8 in, what would happen to the mean?
It would decrease.
Given the following sample data 8.68.49.310.59.88.910.2 If a new number (=11) is added to this data, what would happen to the mean
It would increase
Which of the following would NOT be an appropriate measure of central tendency when looking at the incomes of a middle-class neighborhood when one neighbor just sold their startup idea to Google for $4,000,000?
Mean
Which of the following statements would correspond to an alternative hypothesis?
The population mean is not 22
Which of the following statements would correspond to a null hypothesis?
The population proportion is at most 0.75
Let Z be the random variable which has the standard normal distribution. Which of the following is NOT a property of the the standard normal distribution?
The potential values of Z are from −3 to 3
If a population is heavily skewed to the right, can we use the central limit theorem?
Yes, if enough samples are taken.
The mean score on a standardized math exam is 75; the standard deviation is 8. Zack is told that the z-score of his exam score is -1.25. Which of the following statements is true?
Zack's score is below the class average.
The Department of Education wishes to estimate the proportion of all college students who have a job off-campus. It surveyed 1600 randomly selected students; 451 had such jobs. The population of interest to the Department of Education is:
all college students
18% of victims of financial fraud know the perpetrator of the fraud personally. Let X be the number of people in a random sample of 24 victims of financial fraud who knew the perpetrator personally. Then X is binomial with:
n=24 p=0.18
In a random sample of 14 people, the mean body mass index (BMI) was 25.7 and the standard deviation was 5.12. Assume the body mass indexes are normally distributed. Which distribution will you use to calculate a confidence interval for BMI?
t distribution
Let � be the number you observe when you randomly roll a fair 6-sided die. An experiment consists of taking 1000 such rolls (i.e., sample size n = 1000). Let �¯ be the average value of these 1000 rolls. Does �¯ follow approximately a normal distribution?
true
Which of the following is NOT a property of the standard normal distribution?
uniform in shape
A researcher wishes to estimate the average amount spent per person by visitors to a museum. She takes a random sample of forty-five visitors and obtains an average of$26 per person. The population of interest is
visitors to the museum.
Let X be the number you observe when you randomly roll a fair 6-sided die and suppose that the distribution of X is unknown. An experiment consists of taking 1000 such rolls (i.e., sample size n = 1000). Let �¯ be the average of 1000 rolls. Does �¯ follow approximately a normal distribution?
yes
In a random sample of 55 people, the mean body mass index (BMI) was 25.7 and the standard deviation was 5.12. Assume the body mass indexes are normally distributed. Which distribution will you use to calculate a confidence interval for BMI?
z distribution
