Practice Questions - Hypothesis testing

1. For each situation, find the z (critical).
1. α = 0.05 One tailed
2. α = 0.10 Two tailed
2. For each situation find the t (critical)
1. α = 0.10, two tailed, N = 31
2. α = 0.02, two-tailed, N = 24
3. α = 0.01, one-tailed, N = 31
3. Compute the appropriate test statistic (Z or t) for each situation:
1. µ = 2.40; σ = 0.75; Xbar (sample mean) = 2.20; N = 200
2. µ = 17.1; Xbar = 16.8; s = 0.9; N = 45
3. µ = 10.2; Xbar = 9.4; s = 1.7; N = 150
4. Nationally the average score on the college entrance exams is 453 with a standard deviation of 95. A random sample of 152 freshmen entering St Statistics University shows a mean score of 502. Is there a significant difference?
5. A random sample of 113 convicted rapists in a prison system completed a program designed to change their attitudes toward women, sex and violence before being released. 58 eventually become repeat sex offenders. Is this repeat rate significantly different from the rate of all offenders in this prison system (57%). Summarize your conclusions in a sentence or two.