Number Series — Missing & Wrong Term — Practice

Question 1

4, 6, 9, 13.5, ?
(a) 18  (b) 20.25  (c) 21  (d) 19.5

Accepted Answer

×1.5 each (6/4 = 1.5). 13.5 × 1.5 = 20.25.

Answer: (b) 20.25. The .5 decimal signalled a fractional multiplier.

Question 2

2, 5, 10, 17, 26, ?
(a) 35  (b) 37  (c) 39  (d) 36

Accepted Answer

Differences 3,5,7,9 (odd) ⇒ terms are n²+1. Next = 6²+1 = 37.

Answer: (b) 37.

Question 3

2, 3, 8, 27, ?
(a) 112  (b) 108  (c) 96  (d) 128

Accepted Answer

×1+1, ×2+2, ×3+3 ⇒ next ×4+4 = 27×4+4 = 112.

Answer: (a) 112.

Question 4

1, 3, 7, 13, 21, ?
(a) 29  (b) 31  (c) 33  (d) 30

Accepted Answer

Gaps 2,4,6,8 ⇒ next gap 10; 21+10 = 31.

Answer: (b) 31.

Question 5

Which term is wrong: 5, 11, 23, 48, 95, 191?
(a) 23  (b) 48  (c) 95  (d) 191

Accepted Answer

Rule ×2+1: 5→11→23→47→95→191. The 48 should be 47.

Answer: (b) 48.

Question 6

Which term is wrong: 3, 5, 12, 38, 154, 809?
(a) 12  (b) 38  (c) 154  (d) 809

Accepted Answer

Rule ×1+2, ×2+2, ×3+2, ×4+2, ×5+2: 3→5→12→38→154→772. Given 809 ≠ 772.

Answer: (d) 809.

Practice — Number Series — Missing & Wrong Term