Series Completion - Verbal and Reasoning

Directions to SolveChoose the correct alternative that will continue the same pattern and replace the question mark in the given series.
Q1:

6, 11, 21, 36, 56, ?

A 42

B 51

C 81

D 91

ANS:C - 81

Explanation: The pattern is + 5, + 10, + 15, + 20, ... So, missing term = 56 + 25 = 81.