Slim Easy, a company offers weight-loss programs, states that 25% of its customers loss more than 15 pounds upon finishing its 6-month program. The company has also learned that the weight loss of completing its 6 - month program is normally distributed with an interquartile range of 9 pounds.

A. WHat are the mean and standard deviation of weight loss of completing Slim Easy's 6 - month program?

B. My colleague Mike is going to join this program, what is the probability that he ill lose more than 20 pounds after 6 months?

C. Three of my colleagues join this program, what is the probability that all three of them lose less than 4 pounds after 6 months?