1. Data is gathered from 20 inmates to measure the effects of sensory deprivation; alpha brain-wave frequencies were measured after 7 days in solitary confinement and again after 7 days in their own cell

2. The State Superintendent of Schools consistently states that the average salary of all substitute teachers in every school district is at least $60 per day. The president of the teachers' union believes that the average salary is less than $60 per day. She sampled eight school districts to help test her claim. The daily salaries she found for the districts were $60, $56, $60, $55, $70, $55, $60, and $55.

3. Nationwide, it is estimated that 40% of service stations have gas tanks that leak to some extent. California is trying to lessen the prevalence of these leaks. We want to assess the effectiveness of their efforts by seeing if the percentage of service stations whose tanks leak has decreased. To do this, we randomly sample 27 service stations in California and determine that only 7 of the stations have tanks that leak. Is there evidence that California's efforts are effective? 4. Some insomnia patients are given a drug and others are given a placebo; which subjects sleep more hours?