The Stop N’ Go convenience chain recently selected a random sample of 10 customers. The store monitored the number of times each customer made a purchase at the store over a two-month period. The following data were collected:
10 19 17 19 12 20 20 15 16 13
a. Store executives are considering a promotion in which they reward frequent purchases with a small gift. They have decided that they will only give gifts to those shoppers whose number of visits in the previous two-month period is above the mean plus one standard deviation. Find the minimum number of visits required to receive a price.
Find the mean first = sum of scores/number of scores
Subtract each of the scores from the mean and square each difference. Find the sum of these squares. Divide that by the number of scores to get variance.
Standard deviation = square root of variance
I'll let you do the calculations.
posted by PsyDAG