Find the next term in the given series.
1S, 3Q, 7M, 15K, ?
Show answer & explanation
Correct answer: A
Explanation
Number part
1, 3, 7, 15
Pattern:
1 × 2 + 1 = 3
3 × 2 + 1 = 7
7 × 2 + 1 = 15
15 × 2 + 1 = 31
Next number = 31
Letter part
S, Q, M, K
Position of letters:
S = 19
Q = 17 (−2)
M = 13 (−4)
K = 11 (−2)
Total change here:
19 → 17 → 13 → 11
The differences are −2, −4, −2, respectively. The next term will again be −4:
11 − 4 = 7 = G
Hence, the next term: 31G
Correct answer: (a) 31G