1. The duration of time from first exposure to HIV infection to AIDS diagnosis is called the incubation period. The incubation periods of a random sample of 14 HIV infected individuals is given below (in years): $12.0,10.5,5.2,9.5,6.3,13.1,13.5, 12.5, 10.7, 7.2,14.9$, $6.5,8.1,7.9$. (a) Calculate the sample mean, median, and range. (b) Calculate the sample standard deviation. (c) Calculate the coefficient of variation. (d) Calculate the $25^{\text {th }}$ and $80^{\text {th }}$ quantiles. SP.SS. 371