Series Completion - Section 1

 

Series Completion - Section 1

 

Directions to Solve

Choose the correct alternative that will continue the same pattern and replace the question mark in the given series.

 

Series Completion - Section 1

1.120, 99, 80, 63, 48, ?

A.35

B.38

C.39

D.40

Answer: Option-A

Explanation:The pattern is - 21, - 19, - 17, - 15,.....

So, missing term = 48 - 13 = 35.

2. 589654237, 89654237, 8965423, 965423, ?

A.58965

B.65423

C.89654

D.96542

Answer: Option-D

Explanation:The digits are removed one by one from the beginning and the end in order alternately

so as to obtain the subsequent terms of the series.

3. 3, 10, 101,?

A.10101

B.10201

C.10202

D.11012

Answer: Option-C

Explanation:

Each term in the series is obtained by adding 1 to the square of the preceding term.

So, missing term = (101)² + 1 = 10202.

4.In the series 2, 6, 18, 54, ...... what will be the 8th term ?

A.4370

B.4374

C.7443

D.7434

Answer: Option-B

Explanation:

Clearly, 2 x 3 = 6, 6 x 3 = 18, 18 x 3 = 54,.....

So, the series is a G.P. in which a = 2, r = 3.

Therefore 8^th term = ar^8-1 = ar⁷ = 2 x 3⁷ = (2 x 2187) = 4374.

5.125,80,45,20,?

A.5

B.8

C.10

D.12

Answer: Option-A

Explanation:The pattern is - 45, - 35, - 25, .....

So, missing term = 20 - 15 = 5.

6. 1, 1, 4, 8, 9, 27, 16, ?

A.32

B.64

C.81

D.256

Answer: Option-B

Explanation:

The series consists of squares and cubes of consecutive natural numbers i.e. 1², 1³, 2², 2³, 3², 3³, 4², .....

So, missing term = 4³ = 64.

7. 1, 2, 3, 6, 9, 18, ?, 54

A.18

B.27

C.36

D.81

Answer: Option-B

Explanation:The pattern is x 2, x 3/2, x 2, x 3/2, x 2,.....

So, missing term = 18 x 3/2 = 27.

8. 6, 13, 25, 51, 101, ?

A.201

B.202

C.203

D.205

Answer: Option-C

Explanation:The pattern is x 2 + 1, x 2 - 1, x 2 + 1, x 2 - 1,.....

So, missing term = 101 x 2 + 1 = 203.

9. 5, 6, 9, 15, ?, 40

A.21

B.25

C.27

D.33

Answer: Option-B

Explanation:The pattern is + 1, + 3, + 6,....., i.e. + 1, + (1 + 2), + (1 + 2 + 3),.....

So, missing term = 15 + (1 + 2 + 3 + 4) = 25.

10. 1, 3, 4, 8, 15, 27, ?

A.37

B.44

C.50

D.55

Answer: Option-C

Explanation: The sum of any three consecutive terms of the series gives the next term.

So, missing number = 8 + 15 + 27 = 50.

11.3, 4, 7, 7, 13, 13, 21, 22, 31, 34, ?

A.42

B.43

C.51

D.52

Answer: Option-B

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

I. 3, 7, 13, 21, 31, ? and II. 4, 7, 13, 22, 34

The pattern in I is + 4, + 6, + 8, + 10,.....

The pattern in II is + 3, + 6, + 9, + 12,.....

So, missing term = 31 + 12 = 43.

12. 198, 194, 185, 169, ?

A.92

B.112

C.136

D.144

Answer: Option-D

Explanation:

The pattern is - 4, - 9, - 16,.....i.e. - 2², - 3², - 4²,.....

So, missing pattern = 169 - 5² = 169 - 25 = 144.

13.2, 3, 5,7,11,?, 17

A.12

B.13

C.14

D.15

Answer: Option-B

Explanation:Clearly, the given series consists of prime numbers starting from 2. So, the missing

term is the prime number after 11, which is 13.

14. 6, 12, 21, ?, 48

A.33

B.38

C.40

D.45

Answer: Option-A

Explanation:The pattern is + 6, + 9, + 12, + 15, .....

So, missing term = 21 + 12 = 33.

15.Which term of the series 5, 10, 20, 40, ..... is 1280?

A.10th

B.9th

C.8th

D.None of these

Answer: Option-B

Explanation:Clearly, 5 x 2 = 10, 10 x 2 = 20, 20 x 2 = 40,.....

So, the series is a G.P. in which a = 5 and r = 2.

Let 1280 be the rath term of the series.

Then, 5x2^n-1 = 1280 ↔2^n-1 = 256 = 2⁸ ↔ n - 1 = 8 ↔ n = 9.

16.2, 5, 9, ?, 20, 27

A.14

B.16

C.18

D.24

Answer: Option-A

Explanation:The pattern is + 3, + 4, + 5, + 6,.....

So, missing term = 9 + 5 = 14.

17. 2, 3, 3, 5, 10, 13, ?, 43, 172, 177

A.23

B.38

C.39

D.40

Answer: Option-C

Explanation:

The pattern is + 1, x 1, + 2, x 2, + 3, x 3, + 4, x 4, + 5.

So, missing term = 13 x 3 = 39.

18. 9, 27, 31, 155, 161, 1127, ?

A.316

B.1135

C.1288

D.2254

Answer: Option-B

Explanation:The pattern is x 3, + 4, x 5, + 6, x 7,.....

So, missing term = 1127 + 8 = 1135.

19.  2, 1, 2, 4, 4, 5, 6, 7, 8, 8, 10, 11, ?

A.9

B.10

C.11

D.12

Answer: Option-B

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

I. 1st, 4th, 7th, 10th, 13th terms i.e. 2, 4, 6, 8, ?

II. 2nd, 5th, 8th, 11th terms i.e. 1, 4, 7, 10

III. 3rd, 6th, 9th, 12th terms i.e. 2, 5, 8, 11

Clearly, I consists of consecutive even numbers. So, the missing term is 10.

20.Which of the following will not be a number of the series 1, 8, 27, 64, 125,.....?

A.256

B.512

C.729

D.1000

Answer: Option-A

Explanation:The given series consists of cubes of natural numbers only. 256 is not the cube of

any natural number.

21. 13, 32, 24, 43, 35, ?, 46, 65, 57, 76

A.45

B.52

C.54

D.55

Answer: Option-C

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

I. 13, 24, 35, 46, 57 and II. 32, 43, ?, 65, 76

The pattern in both I and II is + 11. So, missing term = 43 + 11 = 54.

22. 22, 24, 28, ?, 52, 84

A.36

B.38

C.42

D.46

Answer: Option-A

Explanation:The pattern is + 2, + 4, + 8, + 16,.....

So, missing term = 28 + 8 = 36.

23. 3, 15, ?, 63, 99, 143

A.27

B.35

C.45

D.56

Answer: Option-B

Explanation:

The terms of the given series are (2² - 1), (4² - 1),....., (8² - 1), (10² - 1), (12² - 1).

So, missing term = (6² - 1) - (36 - 1) = 35.

24. 90, 180, 12, 50, 100, 200, ?, 3, 50, 4, 25, 2, 6, 30, 3

A.150

B.175

C.225

D.250

Answer: Option-A

Explanation:Clearly, 90 = 30 x 3, 180 = 6 x 30, 12 = 2 x 6, 50 = 25 x 2, 100 = 4 x 25, 200 = 50 x 4.

So, missing term = 3 x 50 = 150.

25. 48, 24, 96, 48, 192, ?

A.76

B.90

C.96

D.98

Answer: Option-C

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

So, missing term = 192 ÷ 2 = 96.

26. 2,15,41,80,?

A.111

B.120

C.121

D.132

Answer: Option-D

Explanation:The pattern is + 13, + 26, + 39,.....

So, missing term = 80 + 52 = 132.

27. 6, 11, 21, 36, 56, ?

A.42

B.51

C.81

D.91

Answer: Option-C

Explanation:The pattern is + 5, + 10, + 15, + 20, ...

So, missing term = 56 + 25 = 81.

28. 563, 647, 479, 815, ?

A.672

B.386

C.279

D.143

Answer: Option-D

Explanation:-The pattern is + 84, - 168, + 336,.....i.e. + 84, - (84 x 2), + (84 x 2²), .....

So, missing term = 815 - (84 x 2³) = 815 - 672 = 143.

29.13, 35, 57, 79, 911, ?

A.1110

B.1112

C.1113

D.1315

Answer: Option-C

Explanation:The terms of the given series are numbers formed by joining together consecutive

odd numbers in order i.e. 1 and 3, 3 and 5, 5 and 7, 7 and 9, 9 and 11, .....

So, missing term = number formed by joining 11 and 13 = 1113.

30. 1, 4, 10, 22, 46, ?

A.64

B.86

C.94

D.122

Answer: Option-C

Explanation:The pattern is + 3, + 6, + 12, + 24,.....

So, missing term = 46 + 48 = 94.

31. 66, 36, 18, ?

A.3

B.6

C.8

D.9

Answer: Option-C

Explanation:Each term in the series is the product of the digits of the preceding term.

So, missing term = 1 x 8 = 8.

32.In the series 3, 9, 15, ...... what will be the 21st term?

A.117

B.121

C.123

D.129

Answer: Option-C

Explanation:

Clearly, 3 + 6 = 9, 9 + 6 = 15,.....

So, the series is an A.P. in which a = 3 and d = 6.

Therefore 21st term = a + (21 - 1) d = a + 20d = 3 + 20 x 6 = 123.

33. 28, 33, 31, 36, ?, 39

A.32

B.34

C.38

D.40

Answer: Option-B

Explanation:The pattern is + 5, - 2, + 5, - 2,.....

So, missing term = 36 - 2 = 34.

34.1, 9, 25, 49, 81, ?

A.100

B.112

C.121

D.144

Answer: Option-C

Explanation:The series consists of squares of consecutive odd numbers

i.e. 1², 3², 5², 7², 9²,.....

So, missing term = 11² = 121.

35. 1, 9, 25, 49, ?, 121

A.64

B.81

C.91

D.100

Answer: Option-B

Explanation:The given series consists of squares of consecutive odd numbers

i.e. 1², 3², 5², 7²,.....

So, missing term = 9² = 81.

36. 2,2,5, 13,28,?

A.49

B.50

C.51

D.52

Answer: Option-D

Explanation:

The pattern is + 0, + 3, + 8, + 15, ..... i.e. + (l² - 1), + (2² - 1), + (3² - 1), + (4² - 1), .....

So, missing term = 28 + (5² - 1) = 28 + 24 = 52.

37. 0, 2, 8, 14, ?, 34

A.20

B.23

C.24.

D.25

Answer: Option-C

Explanation:The pattern is + 2, + 6, + 6, + 10, + 10,.....

So, missing term = 14 + 10 = 24.

38. 1, 5, 14, 30, 55, 91, ?

A.130

B.140

C.150

D.160

Answer: Option-B

Explanation:The pattern is + 4, + 9, + 16, + 25, + 36, ..... i.e. + 2², + 3², + 4², + 5², + 6²,.....

So, missing term = 91 + 7² = 91 + 49 = 140.

39.In the series 10, 17, 24, 31, 38,.....which of the following will be a number of the series ?

A.48

B.346

C.574

D.1003

Answer: Option-B

Explanation:The given series consists of numbers each of which, on dividing by 7, leaves a

remainder 3. No other number except 346 satisfies the property.

40. 240, ?, 120, 40, 10, 2

A.180

B.240

C.420

D.480

Answer: Option-B

Explanation:The pattern is ÷ 1, ÷ 2, ÷ 3, ÷ 4, ÷ 5.

So, missing term = 240 ÷ 1 = 240.

41. 2,3,8,27, 112,?

A.226

B.339

C.452

D.565

Answer: Option-D

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

So, missing term = 112 x 5 + 5 = 565.

42. 6, 17, 39, 72, ?

A.83

B.94

C.116

D.127

Answer: Option-C

Explanation:The pattern is + 11, + 22, + 33, .....

So, missing term = 72 + 44 = 116.

43. 20, 20, 19, 16, 17, 13, 14, 11, ?, ?

A.10, 10

B.10, 11

C.13, 14

D.13, 16

Answer: Option-A

Explanation:Let the missing terms of the series be x₁ and x₂.

Thus, the sequence 20, 20, 19, 16, 17, 13, 14, 11, xv x2 is a combination of two series :

I. 20, 19, 17, 14, x₁ and II. 20, 16, 13, 11, x₂

The pattern in I is - 1, - 2, - 3,......So, missing term, x₁ = 14 - 4 = 10.

The pattern in II is - 4, - 3, - 2,......So, missing term, x₂ = 11 - 1 = 10.

44. 24, 60, 120, 210, ?

A.300

B.336

C.420

D.525

Answer: Option-B

Explanation:The pattern is + 36, + 60, + 90,.....i.e. + [6 x (6 + 0)], + [6 x (6 + 4)], + [6 x (6 + 9)],...

So, missing term = 210 + [6 x (6 + 15)] = 210 + 126 = 336.

45. 625, 5, 125, 25, 25, ?, 5

A.5

B.25

C.125

D.625

Answer: Option-C

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

I. 625, 125, 25, 5 and II. 5, 25, ?

The pattern in I is ÷ 5, while that in II is x 5. So, missing term = 25 x 5 = 125.

46. 10, 100, 200, 310, ?

A.400

B.410

C.420

D.430

Answer: Option-D

Explanation:The pattern is + 90 + 100, + 110,.....

So, missing term = 310 + 120 = 430.

47.  11, 10, ?, 100, 1001, 1000, 10001

A.101

B.110

C.111

D.None of these

Answer: Option-A

Explanation:The pattern is - 1, x 10 + 1, - 1, x 10 + 1, - 1, x 10 + 1, .....

So, missing term = 10 x 10 + 1 = 101.

48. 2, 7, 27, 107, 427, ?

A.1262

B.1707

C.4027

D.4207

Answer: Option-B

Explanation:

The pattern is + 5, + 20, + 80, + 320, ...... i.e. + (5 x 1²), + (5 x 2²), + (5 x 4²), + (5 x 8²),.....

So, missing term = 427 + (5 x 16²) = 427 + 1280 = 1707.