In the following number series only one is wrong. Find out the wrong number. 7, 4, 5, 9, 20, 51, 106.5 ?
A . 4
B . 5
C . 9
D . 20
E . 51
Answer : E . 51
Explanation:
The series is x 0.5 + 0.5, x 1 + 1, x 1.5 + 1.5. x 2 + 2, x 2.5 + 2.5, x 3 +3