1. A random sample of 300 high school seniors was given the ACT-V test. The mean score for this sample was 24. Assuming that the population is normally distributed, what would the mean score μ for all high school students be?
a. 300
b. 24
c. 12.5
d. 11.5
2. What is the critical value that corresponds to a 95% confidence level?
a. +/- 1.96
b. +/- 2.28
c. +/- 2.575
d. +/- 1.645
3. Given the sample statistics, which level of confidence will produce the narrowest results?
a. 75%
b. 85%
c. 95%
d. 99%
4. A 95% confidence interval for the population proportion of college students that eat in the school cafeteria 5 times a week is 62.2% < p < 64.4%. Which answer choice best interprets the results of this confidence interval?
a. We are 5% confident that the true population proportion of college students that eat in the school cafeteria 5 times a week is between 62.2% and 64.4%.
b. We are 5% confident that the true population proportion of college students that eat in the school cafeteria 5 times a week is greater than 64.4%.
c. We are 95% confident that the true population proportion of college students that eat in the school cafeteria 5 times a week is between 62.2% and 64.4%.
d. We are 95% confident that the true population proportion of college students that eat in the school cafeteria is less than 62.2%.
5. You are interested in estimating, with 90% confidence, the population proportion of U.S. adults who stated that football was their favorite sport. The estimate that you obtain must be within 3% of the population proportion. If no prior estimate of the proportion is available, what is the sample size that you need to meet this requirement?
a. 1067
b. 752
c. 807
d. 925
6. A statistics teacher wants to estimate the mean math score for the population of statistics students. How many statistics students must be randomly selected for the math test if he wants 95% confidence that the sample mean is within 23 points of the population mean? The population standard deviation on the SAT math test is 125.
a. 113
b. 110
c. 114
d. 120
7. In a random sample of 25 patients, the mean waiting time to be seen by the nurse was 37 minutes. The population has a normal distribution. You want to construct a 95% confidence interval. Which distribution should you use and why?
a. Normal distribution because the population has a normal distribution.
b. Neither the normal distribution nor the T-distribution because the sample is too small.
c. Normal distribution because the mean waiting time was 37 minutes and the population has a normal distribution.
d. T-distribution because the sample is small, the population is normally distributed, and the standard deviation is unknown.
8. A 99% confidence interval estimate of the population standard deviation of the time (in minutes)that all students spend online studying is
15 Which answer choice best interprets theresults of this confidence interval?
a. We are 1% confident that the true population standard deviation of the time that students
spend online studying is between 15 and 19 minutes.
b. We are 2% confident that the true population standard deviation of the time that students
spend online studying is greater than 19 minutes.
c. We are 95% confident that the true population standard deviation of the time that
students spend online studying is less than 15 minutes.
d. We are 99% confident that the true population standard deviation of the time that
students spend online studying is between 15 and 19 minutes.