Question

Determine the number that shall come in place of ? in the given series:
8    13    10    15    12    ?

• A. 13
• B. 14
• C. 16
• D. 20
• E. 17

Hint:

When a series seems irregular, separate it into odd-indexed and even-indexed terms. Each sub-series often follows a simple arithmetic or geometric pattern.

Answer 1

Answer: (E)

Step 1: Understanding the Concept:
This is a number series question with an alternating two-pattern structure.

Step 2: Detailed Explanation:
Odd-positioned terms: 8, 10, 12, ? \(\to\) each increases by 2. Next odd-position term = \(12 + 2 = 14\) (position 7).
Even-positioned terms: 13, 15, ? \(\to\) each increases by 2. Next = \(15 + 2 = 17\).
The 6th term is in the even-position group. So ? = 17.

Step 3: Final Answer:
The missing number is 17.