1. A researcher wants to know if the average time in jail for robbery has increased from what it was several years ago when the average sentence was 7 years. He obtains data on 400 more recent robberies and finds an average time served of 7.5 years. If we assume the standard deviation is 3 years, what is the P-value of the test?
A. 0.0004
B. 0.0008
C. 0.9996
2. A researcher wants to know if the average time in jail for robbery has increased from what it was several years ago when the average sentence was 7 years. He obtains data on 400 more recent robberies and finds an average time served of 7.5 years. If we assume the standard deviation is 3 years, a 95% confidence interval for the average time served is
A. (7.25, 7.75)
B. (7.21, 7.79)
C. (7.11, 7.89)
3. A researcher reports that a test is "significant at 5%." This test will be
A. significant at 1%.
B. not significant at 1%.
C. significant at 10%.