A random sample of 49 medical doctors in LA showed that they worked an average of 53.1 hours/week with a standard deviation of 7.2 hours/week. If the California average is 60 hours/week, does this give evidence that the LA doctors work significantly less than the rest of California?

USA Today reported that in 1992, 39% of all elementary school children claimed that when they grow up they want to do something to help other people. However, in 1995, 128 of a random sample of 317 of these same children claimed that when they grow up they want to do something to help other people. Does this information indicate that there has been an attitude change either way?

The manager of a sporting goods store offered a bonus commission to his salespeople when they sold moregoods. A new manager dropped the bonus system. For a random sample of six sales people, the weeklysales (in thousands of dollars) are shown in the following table with and without the bonus system

Salesperson 1 2 3 4 5 6

with bonus 2.9 3.0 5.8 4.4 5.3 5.6

w/o bonus 2.8 2.5 5.9 3.5 4.6 4.6

difference 0.1 0.5 -0.1 0.9 0.7 1.0