Number Series - Verbal and Reasoning

Directions to SolveLook carefully for the pattern, and then choose which pair of numbers comes next.
Q1:

Look at this series: 4, 7, 25, 10, __, 20, 16, 19, ... What number should fill the blank?

A 13

B 15

C 20

D 28

ANS:A - 13

Two series alternate here, with every third number following a different pattern. In the main series, 3 is added to each number to arrive at the next. In the alternating series, 5 is subtracted from each number to arrive at the next.