Given the series: 4, 7, 12, 21, 38, .. What is the seventh term?

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10 Jun 2020 Series

Given the series:
4, 7, 12, 21, 38, ..
What is the seventh term?

OPtion

1) 81
2) 71
3) 126
4) 136
5) 96
6) 91
7) 98
8) 102
9) 101
10) None of these

Solution

Series is formed by adding 2^n+1 in previous number
So
4 + 2^1+1 = 7
7 + 2^2+1 = 12
12 + 2^3+1 = 21
21 + 2^4+1 = 38
38 + 2^5+1 = 71
71 + 2^6+1 = 136

Correct Option: 4 Best Solution (3)