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1. Which of the following is a true statement?
2. Two classes take the same exam. Suppose a certain score is at the 40th percentile for the first class and at the 80th percentile for the second class. Which of the following is the most reasonable conclusion?
3. In an experiment, the control group should receive
4. In a random sample of Toyota car owners, 83 out of 112 said they were satisfied with the Toyota front-wheel drive, while in a similar survey of Subaru owners, 76 out of 81 said they were satisfied with the Subaru four-wheel drive. A 90% confidence interval estimate for the difference in proportions between Toyota and Subaru car owners who are satisfied with their drive systems is reported to be -0.197 ± 0.081. Which is a proper conclusion?
5. In a study on the effect of music on worker productivity, employees were told that a different genre of background music would be played each day and the corresponding production outputs noted. Every change in music resulted in an increase in production. This is an example of
6. A computer manufacturer sets up three locations to provide technical support for its customers. Logs are kept noting whether or not calls about problems are solved successfully. Data from a sample of 1000 calls are summarized in the following table:
Assuming there is no association between location and whether or not a problem is resolved successfully, what is the expected number of successful calls (problem solved) from location 1?
7. Which of the following statements about the correlation coefficient is true?
8. Suppose X and Y are random variables with E(X) = 780, var(X) = 75, E(Y) = 430, and var(Y) = 25. Given that X and Y are independent, what is the variance of the random variable X - Y?
9. What is a sample?
10. A histogram of the cholesterol levels of all employees at a large law firm is as follows:
Which of the following is the best estimate of the standard deviation of this distribution?