15, 30, 55, 90, ?, 210

Find out the missing number in the following number series.

Q. 15, 30, 55, 90, ?, 210

A.125

B.135

C.145

D.155

E.165

Sol:

15 + 5 * 3 = 30

30 + 5 * 5 = 55

55 + 5 * 7 = 90

90 + 5 * 11 = 145

145 + 5 * 13 = 210