Number Series Questions and Answers Part-18

1. Find out the wrong term: 1, 3, 12, 25, 48
a) 3
b) 12
c) 25
d) 48

Explanation: The terms of the series are (12 - 0), (22 - 12 ), (42 - 22 ), (62 - 32 ), and (82 - 42 ),
So, 25 is wrong and must be replaced by (62 - 32) i.e., 27.

2. Find out the wrong term: 2, 3, 4, 4, 6, 8, 9, 12, 16
a) 3
b) 6
c) 9
d) 12

Explanation: The given sequence is a combination of three series:
I: 1st, 4th, 7th terms i.e., 2, 4, 9.....
II: 2nd, 5th, 8th terms i.e.,3, 6, 12.......
III: 3rd, 6th, 9th terms i.e., 4, 8, 16..................
In each one of I, II and III, each term is twice the preceding term.
So, 9 is wrong and must be replaced by (4 × 2) i.e., 8.

3. Find out the wrong term: 3, 2, 8, 9, 13, 22, 18, 32, 23, 42
a) 8
b) 9
c) 13
d) 22

Explanation: The given sequence is a combination of two series:
I: 3, 8, 13, 18, 23 and
II: 2, 9, 22, 32, 42
The pattern in I: is + 5, and the pattern in II: is + 10
So, in II, 9 is wrong and must be replaced by (2 + 10) i.e., 12.

4. Find out the wrong term: 1236, 2346, 3456, 4566, 5686
a) 1236
b) 3456
c) 4566
d) 5686

Explanation: The correct pattern in the series is + 1110.
So, 5686 is wrong and must be replaced by (4566 + 1110) i.e., 5676.

5. In a given series one term is wrong or missing term: 1, 5, 14, 30, 55, 93
a) 97
b) 95
c) 93
d) 55

Explanation: The correct pattern is + 4, + 9, + 16, + 25,+ 36 i.e., + 22, + 32 , + 42 , + 52 , + 62
So, 93 is wrong and must be replaced by (55 + 36) i.e., 91.

6. Find out the wrong term: 1, 2, 4, 8, 16, 32, 64, 96,
a) 4
b) 32
c) 64
d) 96

Explanation: Each term of the series is obtained by multiplying the preceding term by 2.
So, 96 is wrong and must be replaced by (64 × 2) i.e., 128.

7. Find out the wrong term: 125, 126, 124, 127, 123, 129
a) 126
b) 124
c) 123
d) 129

Explanation: The correct pattern is + 1, - 2, + 3, - 4, + 5.
So, 129 is wrong and must be replaced by (123 + 5) i.e., 128

8. Find out the wrong term: 15, 16, 22, 29, 45, 70
a) 16
b) 22
c) 45
d) 70

Explanation: The correct pattern is + 1, + 4, + 9, + 16, + 25 i.e., + 12 , + 22 , + 32 , + 42 , + 52.
So, 22 is wrong and must be replaced by (16 + 4) i.e., 20.

9. Find out the wrong term: 105, 85, 60, 30, 0, - 45, - 90
a) 105
b) 60
c) 0
d) 45