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 (1

^{2}- 0), (2

^{2}- 1

^{2}), (4

^{2}- 2

^{2}), (6

^{2}- 3

^{2}), and (8

^{2}- 4

^{2}),

So, 25 is wrong and must be replaced by (6

^{2}- 3

^{2}) 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., + 2

^{2}, + 3

^{2}, + 4

^{2}, + 5

^{2}, + 6

^{2}

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., + 1

^{2}, + 2

^{2}, + 3

^{2}, + 4

^{2}, + 5

^{2}.

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

Explanation: The correct pattern is - 20, - 25, - 30, ............

So, 0 is wrong and must be replaced by (30 - 35) i.e., - 5.

10. Find out the wrong term: 56, 58, 62, 70, 84, 118, 182

a) 58

b) 62

c) 84

d) 118

Explanation: The correct pattern is + 2, + 4, + 8, + 16, + 32, + 64 i,e., + 2, + 2

^{2}, + 2

^{3}, + 2

^{4}, + 2

^{5}, + 2

^{6}.

So, 84 is wrong and must be replaced by (70 + 16) i.e., 86.