Sequence and Series Questions and Solutions : Logical Reasoning

  • 1. Which number would replace underline mark in the series? 
    2, 5, 10, 17, ---, 37
A.) 27
B.) 24
C.) 26
D.) 28

Answer: Option 'C'

Here the difference between the consecutive terms is increase by 2 
5 - 2 = 3, 
10 - 5 = 5, 
17 - 10 = 7, 
then 17 + 9 = 26.

  • 2. Which number would replace underline mark in the series?
    1, 6, 26,_____, 426.
A.) 86
B.) 76
C.) 106
D.) 96

Answer: Option 'C'

Here the difference between the consecutive terms is multiplied by 4. 
The difference of the two consecutive numbers is 5, 20, ..... 
5 × 4 = 20 
20 × 4 = 80 
26 + 80 = 106.

  • 3. Which number would replace underline mark in the series?
    1, 20, 58, ____, 191.
A.) 105
B.) 115
C.) 111
D.) 116

Answer: Option 'B'

Here the difference between the two consecutive terms is 19, 38, 57, 76 
58 + 57 = 115

  • 4. 2, 10, 40, 120,____
A.) 240
B.) 360
C.) 470
D.) 210

Answer: Option 'A'

Here the series is a multiplication series.
The order of the multiplication is ×5, ×4, ×3, ×2 
120 × 2 = 240

  • 5. 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