Question

What should come in place of the question mark (?) in the given series? 7 12 16 30 34 66 70 ?

• A. 136
• B. 138
• C. 142
• D. 140

Answer 1

Answer:

B. 138

Let’s split the series into two alternating patterns:

Series:
7, 12, 16, 30, 34, 66, 70, ?

Observe alternating pairs

Odd positions:
7, 16, 34, 70

Even positions:
12, 30, 66, ?

Check pattern in odd terms

7 → 16 → 34 → 70

Differences:
+9, +18, +36 (doubling each time)

Check pattern in even terms

12 → 30 → 66 → ?

Differences:
+18, +36, +72 (doubling each time)

So next difference = 72

66 + 72 = 138

Final Answer: 138