According to Business Week, Maternity Chic, a purveyor of designer maternity wear, sells dresses and pants priced around $150 each for an average total sale of $1,200. The total sale has a normal distribution with a standard deviation of $350.
a. Calculate the probability that a randomly selected customer will have a total sale of more than $1,500.
b. Compute the probability that the total sale will be within 2 standard deviations of the mean total sales.
c. Determine the median total sale.

Question

Mercury · Answer

a. you are given mean (1,200) and standard deviation (350). calculate the z-score for the value of 1,500 then use a z-table (or a calculator) to find the associated probability. since you want the total sale to be *above* 1,500, take 1 - (the value from the table).

b. within two standard deviations: look at a normal distribution curve and find the % that lies between +2 and -2 standard deviations

c. for normal distributions, median = mean = already given in problem