In a study to determine whether counseling could help people lose weight, a sample of people experienced a group-based behavioral intervention, which involved weekly meetings with a trained interventionist for a period of six months. The following data are the numbers of pounds lost for 

14

people, based on means and standard deviations given in the article. Assume the population is approximately normal. Perform a hypothesis test to determine whether the mean weight loss is greater than18

pounds. Use the=

α

0.10

level of significance and the critical value method.20.4

26.6

5.7

22.1

19.1

10.7

15.7

19.0

35.6

31.8

10.3

33.8

21.7

17.4