A student needs to select 3 books from 3 different mathematics, 3 different physics and 1 history book. what is the probability that one of them is mathematics and the other 2 are either physics or history books ? A. 3/15 B.9/25 C. 15/35 D. 18/35​

Arandom sample of 15 observations is used to estimate the population mean. the sample mean and the standard deviation are calculated as 172 and 63, respectively. assume that the population is normally distributed. a. with 99 confidence, what is the margin of error for the estimation of the population mean? b. construct the 99% confidence interval for the population mean. c. construct the 95% confidence interval for the population mean. d. construct the 83% confidence interval for the population mean. hint: you need to use excel function =t. inv.2t to find the value of t for the interval calculation.