Cadbury, Inc., is interested in estimating people's responses to a new chocolate. The company believes that people in different age groups differ in their prefer- ences for chocolate. The company believes that in the region of interest, 25% of the population are children, 55% are young adults, and 20% are older people. A proportional allocation of a total random sample of size 1,000 is undertaken, and people's responses on a scale of 0 to 100 are solicited. The results are as follows. For the chil- dren, x = 90 and s = 5; for the young adults, x = 82 and s = 11; and for the older people, x = 88 and s = 6. Give a 95% con?dence interval for the population average rating for the new chocolate.