1. Use the data below to compute the expected age (mu) of a super shopper. Round your answer to the nearest hundredth.

Marketing:  Age  What is the age distribution of promotion-sensitive shoppers?  A supermarket super shopper is defined as a shopper for whom at least 70% of the items purchased were on sale or purchased with a coupon.  The following table is based on information taken from Trends in the United States (Food Marketing Institute, Washington, D.C.)

Age range, years

18-28 29-39 40-50 51-61 62 and over

Midpoint x

23 34 45 56 67

Percent of super shoppers

7% 44% 24% 14% 11%

2. Use the information below to calculate the standard deviation (sigma) for the ages of nurses shown in the distribution. Round your answer to the nearest hundredth.

History:  Florence Nightingale  What is the age distribution of nurses in Great Britain at the time of Florence Nightingale?  Thanks to Florence Nightingale and the Birth Census of 1851, we have the following information (based on data from the classic text Notes on Nursing, by Florence Nightingale).  Note:  In 1851, there were 25,466 nurses in Great Britain.  Furthermore, Nightingale made a strict distinction between nurses and domestic servants.

Age Range (yr)

20-29 30-39 40-49 50-59 60-69 70-79 80+

Midpoint x

24.5 34.5 44.5 54.5 64.5 74.5 84.5

Percent of nurses

5.7% 9.7% 19.5% 29.2% 25.0% 9.1% 1.8%