QUESTION 8

(a) A marketing study found that the mean spending in 15 categories of consumer items for 150 respondents in the 18 to 34 age group was RM75.50 with a standard deviation of RM53.20. For 250 respondents in the 35+ age group, the mean and the standard deviation were RM65.20 and RM46.10, respectively. Test the hypothesis that there is no difference in the mean spending between these two populations. Use a significance level of 0.05. (Note: Assume that the population variances are not equal). 

(b) In a study of memory recall, ten students from a large statistics and data analysis class were selected at random and given 15 minutes to memorize a list of 20 nonsense words. Each was asked to list as many of the words as he or she could remember both 1 hour and 24 hours later. The data are as shown in Table 1. Is there evidence to suggest the mean number of words recalled after 1 hour exceeds the mean recall after 24 hours by more than 3? Use a significance level of 0.05.

Table 1 Student 1 2 3 4 7 8 10 I hour later 14 12 18 7 11 9. 16 15 13 17 (words) 24 hour later 10 4 14 5 8 11 12 10 (words)