series completion verbal reasoning questions

Directions to Solve

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

31.

66, 36, 18, ?
A.     3    B.     6
C.     8    D.     9
Answer & Explanation

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.

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32.

In the series 3, 9, 15, …… what will be the 21st term?
A.     117    B.     121
C.     123    D.     129
Answer & Explanation

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.

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33.

28, 33, 31, 36, ?, 39
A.     32    B.     34
C.     38    D.     40
Answer & Explanation

Answer: Option B

Explanation:

The pattern is + 5, – 2, + 5, – 2,…..

So, missing term = 36 – 2 = 34.

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34.

1, 9, 25, 49, 81, ?
A.     100    B.     112
C.     121    D.     144
Answer & Explanation

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.

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35.

1, 9, 25, 49, ?, 121
A.     64    B.     81
C.     91    D.     100
Answer & Explanation

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.