(a) You are thinking of using a t procedure to test hypotheses about the mean of a population using a significance level of 0.05. You suspect the distribution of the population is not normal and may be moderately skewed. Which of the following statements is correct?

A. You should not use the t procedure because the population does not have a normal distribution.
B. You may use the t procedure, provided your sample size is large, say at least fifty.
C. You may not use the t procedure. t procedures are robust to nonnormality for confidence intervals but not for tests of hypotheses.
D. You may use the t procedure, but you should probably only claim the significance level is 0.10.

(b) Suppose we were not sure if the distribution of a population was normal. In which of the following circumstances would we NOT be safe using a t procedure?

A. The sample standard deviation is large.
B. The mean and median of the data are nearly equal.
C. A histogram of the data shows moderate skewness.
D. A stemplot of the data has a large outlier.

(c) Which of the following is an example of a matched pairs design?

A. A teacher compares the scores of students using a computer based method of instruction with scores of other students using a traditional method of instruction.
B. A teacher calculates the average scores of students on a pair of tests and wishes to see if this average is larger than 80%.
C. A teacher compares the scores of students in her class on a standardized test with the national average score.
D. A teacher compares the pre-test and post-test scores of students.