Question

A survey of 200 customers was conducted at a particular Cosmic Coffee location. About how many of the customers surveyed spend over $5.25 on a drink? Remember that the mean price is $4.25 with a standard deviation of $0.67.

Answer 1

The z-score is . Using the standard normal table, we see that a z-score of 1.49 is associated with a value of 0.93189. This value represents a probability of 0.93189 that a customer spends less than $5.25 on a drink. The probability of spending over $5.25 is equal to 1 – 0.93189 = 0.06811. Because 200 customers were surveyed, the number that spend over $5.25 on a drink is equal to 0.06811(200) = 13.622, or about x = 14 people.