Series Completion - Section 3

 

Series Completion - Section 3

Directions to Solve

In this type of questions, one term in the number series is wrong. Find out the wrong term.

1. 121, 143, 165, 186, 209

A.143

B.165

C.186

D.209

Answer: Option-C

Explanation:Each term in the series is obtained by adding 22 to the preceding term.

So, 186 is wrong and must be replaced by (165 + 22) i.e. 187.

2. 6, 15, 35, 77, 165, 221

A.35

B.77

C.165

D.15

Answer: Option-C

Explanation:The terms of the series are products of two consecutive prime numbers i.e. (2 x 3),

(3 x 5), (5 x 7), (7 x 11),.....

So, 165 is wrong and must be replaced by (11 x 13) i.e. 143.

3.8, 13, 21, 32, 47, 63, 83

A.13

B.21

C.32

D.47

Answer: Option-D

Explanation:The correct pattern is + 5, + 8, + 11, + 14,.....

So, 47 is wrong and must be replaced by (32 + 14) i.e. 46.

4. 1, 2, 4, 8, 16, 32, 64, 96

A.4

B.32

C.64

D.96

Answer: Option-D

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 x 2) i.e. 128.

5. 3, 4, 10, 32, 136, 685, 4116

A.10

B.32

C.136

D.4116

Answer: Option-B

Explanation:The correct pattern is x 1 + 1, x 2 + 2, x 3 + 3, x 4 + 4,.....

So, 32 is wrong and must be replaced by (10 x 3 + 3) i.e. 33.

6. 105, 85, 60, 30, 0, - 45, - 90

A.105

B.60

C.0

D.-45

Answer: Option-C

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

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

7. 2, 5, 10, 17, 26, 37, 50, 64

A.17

B.26

C.37

D.64

Answer: Option-D

Explanation:The terms of the series are (1² + 1), (2² + 1), (3² + 1), (4² + 1), (5² + 1), (6² + 1),

(7²+1),.....

So, 64 is wrong and must be replaced by (8² + 1) i.e. 65.

8. 125, 126, 124, 127, 123, 129

A.126

B.124

C.123

D.129

Answer: Option-D

Explanation:The correct pattern is + 1, - 2, + 3, - 4, + 5.

So, 129 is wrong and must be replaced by (123 + 5) i.e. 128.

9.  2, 5, 10, 50, 500, 5000

A.5

B.10

C.50

D.5000

Answer: Option-D

Explanation:Each term of the series is the product of the preceding two terms.

So, 5000 is wrong and must be replaced by (50 x 500) i.e. 25000.

10. 1,3,12,25,48

A.3

B.12

C.25

D.48

Answer: Option-C

Explanation:The terms of the series are (l² - 0²), (2² - l²), (4² - 2²), (6² - 3²) and (8² - 4²).

So, 25 is wrong and must be replaced by (6² - 3²) i.e. 27.

11. 15, 16, 22, 29, 45, 70

A.16

B.22

C.45

D.70

Answer: Option-B

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.

12. 8, 14, 26, 48, 98, 194, 386

A.14

B.48

C.98

D.194

Answer: Option-B

Explanation: The correct pattern is x 2 - 2.

So, 48 is wrong and must be replaced by (26 x 2 - 2) i.e. 50.

13.  3, 10, 27, 4, 16, 64, 5, 25, 125

A.3

B.4

C.10

D.27

Answer: Option-C

Explanation:The correct sequence is 3, 3², 3³, 4, 4², 4³, 5, 5², 5³.

So, 10 is wrong and must be replaced by 3² i.e. 9.

14. 1, 5, 9, 15, 25, 37, 49

A.9

B.15

C.25

D.37

Answer: Option-B

Explanation:The terms of the given series are 1², (2² + 1), 3², (4²..+ 1), 5², (6² + 1), 7².

So, 15 is wrong and must be replaced by (4² + 1) i.e. 17.

15. 4, 10, 22, 46, 96, 190, 382

A.4

B.10

C.96

D.382

Answer: Option-C

Explanation:The correct pattern is + 6, + 12, + 24, + 48, + 96, + 192.

So, 96 is wrong and must be replaced by (46 + 48) i.e. 94.

16.2, 6, 24, 96, 285, 568, 567

A.6

B.24

C.285

D.567

Answer: Option-B

Explanation:The correct pattern is x 6 - 6, x 5 - 5, x 4 - 4,.....

So, 24 is wrong and must be replaced by (6 x 5 - 5) i.e. 25.

17. 3, 2, 8, 9, 13, 22, 18, 32, 23, 42

A.8

B.9

C.13

D.22

Answer: Option-B

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.

18. 196, 169, 144, 121, 101

A.101

B.121

C.169

D.196

Answer: Option-A

Explanation:The sequence is (14)², (13)², (12)², (11)², (10)².

So, 101 is wrong and must be replaced by (10)² i.e. 100.

19. 56, 58, 62, 70, 84, 118, 182

A.58

B.62

C.84

D.118

Answer: Option-C

Explanation:The correct pattern is + 2, + 4, + 8, + 16, + 32, + 64 i.e. + 2, + 2², + 2³, + 2⁴, + 2⁵, + 2⁶.

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

20. 1, 5, 5, 9, 7, 11, 11, 15, 12, 17

A.11

B.12

C.17

D.15

Answer: Option-B

Explanation:The given sequence is a combination of two series:

I. 1, 5, 7, 11, 12 and II. 5, 9, 11, 15, 17

The pattern in both I and II is + 4, + 2, + 4, + 2. So, 12 is wrong and must be replaced by (11 + 2) i.e. 13.

21. 25, 36, 49, 81, 121, 169, 225

A.36

B.49

C.169

D.225

Answer: Option-A

Explanation:

The correct sequence is 5², 7², 9², 11², 13², 15². So, 36 is wrong.

22. 1, 3, 10, 21, 64, 129, 356, 777

A.21

B.129

C.10

D.356

Answer: Option-D

Explanation:The correct pattern is x 2 + 1, x 3 + 1, x 2 + 1, x 3 + 1,.....

So, 356 is wrong and must be replaced by (129 x 3 + 1) i.e. 388.

23. 5, 10, 40, 80, 320, 550, 2560

A.80

B.320

C.550

D.2560

Answer: Option-C

Explanation:The correct pattern is x 2, x 4, x 2, x 4, .....

So, 550 is wrong and must be replaced by (320 x 2) i.e. 640.

24. 2, 3, 4, 4, 6, 8, 9, 12, 16

A.3

B.6

C.9

D.12

Answer: Option-C

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 x 2) i.e. 8.

25. 11, 5, 20, 12, 40, 26, 74, 54

A.5

B.20

C.40

D.26

Answer: Option-C

Explanation:The given sequence is a combination of two series :

I. 11, 20, 40, 74 and II. 5, 12, 26, 54

The correct pattern in I is + 9, + 18, + 36,.....

So, 40 is wrong and must be replaced by (20 + 18) i.e. 38.

26.  5, 27, 61, 122, 213, 340, 509

A.27

B.61

C.122

D.509

Answer: Option-A

Explanation:The terms of the series are (2³ - 3), (3³ - 3), (4³ - 3), (5³ - 3), (6³ - 3), (7³ - 3),

(8³-3).

So, 27 is wrong and must be replaced (3³ - 3) i.e. 24.

27. 3, 7, 15, 39, 63, 127, 255, 511

A.15

B.39

C.63

D.127

Answer: Option-B

Explanation:The correct pattern is x 2 + 1.

So, 39 is wrong and must be replaced by (15 x 2 + 1) i.e. 31.

28. 380, 188, 92, 48, 20, 8, 2

A.8

B.20

C.48

D.188

Answer: Option-C

Explanation:The correct pattern is - 192, - 96, - 48, - 24, - 12, - 6.

So, 48 is wrong and must be replaced by (92 - 48) i.e. 44.

29.  16, 22, 30, 45, 52, 66

A.30

B.45

C.52

D.66

Answer: Option-B

Explanation:The correct pattern is + 6, + 8, + 10, + 12, + 14.

So, 45 is wrong and must be replaced by (30 + 10) i.e. 40.

30. 10, 26, 74, 218, 654, 1946, 5834

A.26

B.74

C.218

D.654

Answer: Option-D

Explanation:The correct pattern is x 3 - 4.

So, 654 is wrong and must be replaced by (218 x 3 - 4) i.e. 650.

31. 24576, 6144, 1536, 386, 96, 24

96

386

1536

6144

Answer: Option-B

Explanation:

Each term of the series is obtained by dividing the preceding term by 4.

So, 1536 is wrong and must be replaced by (1536 + 4) i.e. 384.

32.  10, 14, 28, 32, 64, 68, 132

A.28

B.32

C.64

D.132

Answer: Option-D

Explanation:The correct pattern is + 4, x 2, + 4, x 2, .....

So, 132 is wrong and must be replaced by (68 x 2) i.e. 136.

33.  46080, 3840, 384, 48, 24, 2, 1

A.384

B.48

C.24

D.2

Answer: Option-C

Explanation:The correct pattern is ÷ 12, ÷ 10, ÷ 8,÷ 6,.....

So, 24 is wrong and must be replaced by (48 + 6) i.e. 8.

34. 89, 78, 86, 80, 85, 82, 83

A.83

B.82

C.86

D.78

Answer: Option-C

Explanation:The correct pattern is - 11, + 9, - 7, + 5, - 3, + 1.

So, 86 is wrong and must be replaced by (78 + 9) i.e. 87.

35.  0, 2, 3, 5, 8, 10, 15, 18, 24, 26, 35

A.18

B.24

C.26

D.10

Answer: Option-A

Explanation:The given sequence is a combination of two series:

I. 0, 3, 8, 15, 24, 35 and II. 2, 5, 10, 18, 26

The pattern in both I and II is + 3, + 5, + 7, + 9,.....

So, in II, 18 is wrong and must be replaced by (10 + 7) i.e. 17.

36. 325, 259, 202, 160, 127, 105, 94

A.94

B.127

C.202

D.259

Answer: Option-C

Explanation:The correct pattern is - 66, - 55, - 44, - 33, - 22, - 11.

So, 202 is wrong and must be replaced by (259 - 55) i.e. 204.

37. 1236, 2346, 3456, 4566, 5686

A.1236

B.3456

C.4566

D.5686

Answer: Option-D

Explanation:The correct pattern in the series is + 1110.

So, 5686 is wrong and must be replaced by (4566 + 1110) i.e. 5676.

38. 93, 309, 434, 498, 521, 533

A.309

B.434

C.498

D.521

Answer: Option-D

Explanation:The correct pattern is + 6³, + 5³, + 4³, + 3³, .....

So, 521 is wrong and must be replaced by (498 + 3³) i.e. 525.