Question

10_. =20×16
(1) 6
(2) 16 (3) 4

Answer 1

Well there are two series merged, which make one series mentioned above. Lets try to dig into those two.

In first series, number increments by 3, and number appears in the 1,2,4,5,7 positions. Series starts with 4. Numbers in this series are 4,7,10,13,16,19

In second series, number appears at multiple of 3 position. i.e. 3,6,9 ..and it decreases by 5. Starting with 25. So the numbers in this series are 25,20,15 etc.

Combining them together, series becomes 4,7,25,10,13,20,16,19

This kind of series is also known as skip number series and are at times confusing to solve but not very difficult.

Cheers,

PD