Question

et the mean and the variance of 5 observations x1,x2,x3,x4,x5 be 24/5 and 194/25 respectively. If the mean and variance of the first 4 observation are 7/2 and α respectively, then (4a + x5) is equal to:
(A) 13
(B) 15
(C) 17
(D) 18