In the series 3, 9, 15.. what will be the 21st term ?

Answer: Option A

Explanation:

Pattern of the above series is
first + second + 2, second + third + 3, third + fourth + 4......
So next term will be
24 + 41 + 5 = 70

Answer: Option A

Explanation:

Series Pattern is +3, +5, +7, +9.

So next number = 25+11 = 36

Answer: Option D

Explanation:

In this series, each term is the sum of preceding two terms as,
1+2 = 3
3+2 = 5
5+3 = 8
Next term in the series will be,
8+5 = 13

Answer: Option A

Explanation:

Please look carefully at the series, its pattern is,
-1, +2, -1, +2, -1, so next will be +2
23+2 = 25

Answer: Option A

Explanation:

Pattern is +5, +10, +15, + 20. So next will be 56+25 = 81