Find the missing number in the series:
1,3,7,15,?
Show answer & explanation
Correct answer: C
Explanation
Series: 1, 3, 7, 15, ?
Pattern: Multiply by 2 and add 1
1 → 3 = 1×2+1=3
3 → 7 = 3×2+1=7
7 → 15 = 7×2+1=15
Apply to 15
15 × 2 + 1 = 31
Hence, the correct answer is option 3.