Number Series, Coding, Odd Man OutPYQ June 22Question 2027 of 217
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Find the next terms- 3,7,15,31,?,127\displaystyle 3, 7, 15, 31, ?, 127

Options

A62
B63
C64
D65
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Correct Answer

✅ Option b — 63

All Options:

  • A62
  • B63
  • C64
  • D65

Detailed Solution & Explanation

We are given the series: 3,7,15,31,?,127\displaystyle 3, 7, 15, 31, ?, 127
Let's express each term in relation to powers of 2\displaystyle 2:
- 3=22−1\displaystyle 3 = 2^2 - 1
- 7=23−1\displaystyle 7 = 2^3 - 1
- 15=24−1\displaystyle 15 = 2^4 - 1
- 31=25−1\displaystyle 31 = 2^5 - 1
The terms follow the pattern 2k−1\displaystyle 2^k - 1 for consecutive integers k\displaystyle k.
Therefore, the missing term must be 26−1\displaystyle 2^6 - 1:
26−1=64−1=632^6 - 1 = 64 - 1 = 63
Let's verify the next term in the series:
27−1=128−1=1272^7 - 1 = 128 - 1 = 127
This matches the final term perfectly.
Hence, **Option B** is the correct answer.

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