Series Completion Interview Questions and Answers
Question - 21 : - 66, 36, 18, ?
A. 3
B. 6
C. 8
D. 9
Answer - 21 : -
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.
Question - 22 : - In the series 3, 9, 15, ...... what will be the 21st term?
A. 117
B. 121
C. 123
D. 129
Answer - 22 : -
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.
Question - 23 : - 28, 33, 31, 36, ?, 39
A. 32
B. 34
C. 38
D. 40
Answer - 23 : -
Option B
Explanation:
The pattern is + 5, - 2, + 5, - 2,.....
So, missing term = 36 - 2 = 34.
Question - 24 : - 1, 9, 25, 49, 81, ?
A. 100
B. 112
C. 121
D. 144
Answer - 24 : -
Option C
Explanation:
The series consists of squares of consecutive odd numbers
i.e. 12, 32, 52, 72, 92,.....
So, missing term = 112 = 121.
Question - 25 : - 1, 9, 25, 49, ?, 121
A. 64
B. 81
C. 91
D. 100
Answer - 25 : -
Option B
Explanation:
The given series consists of squares of consecutive odd numbers
i.e. 12, 32, 52, 72,.....
So, missing term = 92 = 81.
Question - 26 : - 1, 1, 4, 8, 9, 27, 16, ?
A. 32
B. 64
C. 81
D. 256
Answer - 26 : -
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.
Question - 27 : - 1, 2, 3, 6, 9, 18, ?, 54
A. 18
B. 27
C. 36
D. 81
Answer - 27 : -
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.
Question - 28 : - 5, 6, 9, 15, ?, 40
A. 21
B. 25
C. 27
D. 33
Answer - 28 : -
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.
Question - 29 : - 1, 3, 4, 8, 15, 27, ?
A. 37
B. 44
C. 50
D. 55
Answer - 29 : -
Option C
Explanation:
The sum of any three consecutive terms of the series gives the next term.
So, missing number = 8 + 15 + 27 = 50.
Question - 30 : - 2,15,41,80,?
A. 111
B. 120
C. 121
D. 132
Answer - 30 : -
Option D
Explanation:
The pattern is + 13, + 26, + 39,.....
So, missing term = 80 + 52 = 132.