In questions 9, suppose the marketing manager is interested in the total number of trips to the shopping center in a given month, not in the average number of trips per person for the month.

(a) Estimate the population totals for the two strata, and determine the sample variance of estimation in each case.

(b) Estimate the total for the entire population of males and females, and determine the variance of estimation.

Question 9

A marketing manager is interested in the number of trips per month that people take to a nearby shopping center. Denote the number of trips per month by X.
The manager feels that the variance of X is 16 for women and 9 for men. He decides to stratify by sex, and there are 100 males and 200 females in the population of interest. He takes a random sample of 10 males and another random sample of 15 females and gets the following results:

Transcribed Image Text:

Males 4 2 1 1 1 1 4 7 Females 6 9 12 4 +2 10 5 7 3 2 10 9 7 5 8 16 14 10 8 13