Sequence and Series Questions and Solutions : Logical Reasoning

1.

Find the missing number in the following series. 
2, 3, 6, 15, 45, ?

   A.) 95
   B.) 105.5
   C.) 147
   D.) 157.5

Answer: Option 'D'

2 × 1.5 = 3 
3 × 2 = 6 
6 × 2.5 = 15 
15 × 3 = 45 
45 × 3.5 = 157.5

2.

_CAM_AMC_M_A_CAM

   A.) CMAMC
   B.) MACAM
   C.) MCAMC
   D.) MCACM

Answer: Option 'D'

MCACM

3.

What will be the next term in?
REU, QGV, PIW, QKX, -----

   A.) MOZ
   B.) DEC
   C.) RSE
   D.) NMY

Answer: Option 'D'

NMY

4.

Find the wrong number in the series. 
2, 5, 10, 17, 26, 37, 50, 64

   A.) 5
   B.) 26
   C.) 64
   D.) 17

Answer: Option 'C'

12 + 1, 22 + 1, 32 + 1 ..........82 + 1 = 65

But 64 has been given here. So our wrong number is 64

5.

Look at the series 3.8, 3.5, 3.2, 2.9…… What number should come next?

   A.) 2.7
   B.) 2.6
   C.) 2..5
   D.) 2.8

Answer: Option 'B'

2.6

6.

Find the missing number in the following series. 
12, 53, 207, 618, ?

   A.) 1324
   B.) 1432
   C.) 1234
   D.) 1124

Answer: Option 'C'

12 × 5 - 7 = 53 
53 × 4 - 5 = 207 
207 × 3 - 3 = 618 
618 × 2 - 2 = 1234.

7.

Find the missing number in the following series. 
512, 256, 64, 32, ?

   A.) 16
   B.) 4
   C.) 8
   D.) 10

Answer: Option 'C'

512/2 = 256 
256/4 = 64 
64/2 = 32 
32/4 = 8.

8.

Look at this series: 1000, 200, 40, . . . 
What number should come next?

   A.) 10
   B.) 8
   C.) 9
   D.) 12

Answer: Option 'B'

This is a simple division series.
Each number is divided by 5.
Rule = (1st number / 5 = 2nd number) (2nd number / 5 = 3rd number)....
Now, (1000 / 5 = 200), (200 / 5 = 40), (40 / 5 = 8)...
So answer is a = 8.

9.

18 21 25 18 29 33 18
What numbers should come next ?

   A.) 43 18
   B.) 41 44
   C.) 37 41
   D.) 38 41

Answer: Option 'C'

This is a simple addition series with a random number, 18, interpolated as every third number.
In the series, 4 is added to each number except 18, to arrive at the next number

10.

Look at the series 2, 3, 5, 8, 12….. What number should come next?

   A.) 14
   B.) 15
   C.) 16
   D.) 17

Answer: Option 'D'

17

11.

3 13 18 23 28 33
What number should come next?

   A.) 38 43
   B.) 37 42
   C.) 38 44
   D.) 39 44

Answer: Option 'A'

In this simple addition series, each number is 5 greater than the previous number.
Rule = (1st no) (1st no + 5 = 2nd no) (2nd no + 5 = 3rd no) . . .
Now (3) (3 + 5 = 8) (8 + 5 = 13) (13 + 5 = 18) (18 + 5 = 23) (23 + 5 = 28) (28 + 5 = 33) (33 + 5 = 38) (38 + 5 = 43)
So the answer is c = 38 43

12.

Find the missing number in the following series. 
376, 188, 47, 23.5, ?

   A.) 7.8
   B.) 6.5
   C.) 5.8
   D.) None of these

Answer: Option 'C'

367/2 = 188 
188/4 = 47 
47/2 = 23.5 
23.5/4 = 5.8

13.

Look at this series: 7, 10, 8, 11, 9, 12, . . . 
What number should come next?

   A.) 7
   B.) 10
   C.) 15
   D.) 18

Answer: Option 'B'

This is a simple alternating addition and subtraction series.
In the first pattern, 3 is added;
In the second pattern, 2 is subtracted.
Rule =(1st number) (1st number + 3 = 2nd number) (2nd number - 2 = 3rd number) (3rd number + 3 = 4th number)
Now (7) (7 + 3 = 10) (10 - 2 = 8) (8 + 3 = 11) (11 - 2 = 9) (9 + 3 = 12) (12 - 2 = 10)...
So the answer is b = 10.

14.

What will be the next term in? 
ZAM, YBL, ----, WDJ, VEI

   A.) XCK
   B.) UFH
   C.) ZAC
   D.) PFD

Answer: Option 'A'

XCK

15.

U_VU_WV__WV_

   A.) WUUUU
   B.) UWVUU
   C.) VUWVUV
   D.) NONE

Answer: Option 'A'

WUUUU

16.

Find the wrong number in the series. 
1, 2, 6, 15, 31, 56, 91

   A.) 31
   B.) 71
   C.) 81
   D.) 91

Answer: Option 'D'

The difference odd the two consecutive numbers are
1, 4, 9, 16, 25, 35.
+12, +22, +32,+42,+52,+62
Here 35 is is wrong. wrong answer 91

17.

Find the wrong number in the following series 
6,15,30,75,151,375,750

   A.) 151
   B.) 75
   C.) 375
   D.) 750

Answer: Option 'A'

151

18.

Find the missing number in the following series. 
1050, 506, 236, 105, ?

   A.) 45.5
   B.) 45
   C.) 42.5
   D.) 41.5

Answer: Option 'D'

1050/2 = 525 - 19 = 506 
506/2 = 253 - 17 = 236 
236/2 = 118 - 13 = 105 
105/2 = 52.5 - 11 = 41.5

19.

E_G_EFF_E_FG_FG_EF

   A.) GFGEEE
   B.) FGGGEF
   C.) FGGEEG
   D.) EGFEFG

Answer: Option 'C'

FGGEEG

20.

QQQ_TT__Q_T_Q_Q

   A.) TTQQTT
   B.) QQTQTT
   C.) TQQTTQ
   D.) QTQTTQ

Answer: Option 'C'

TQQTTQ


Sequence and Series Download Pdf