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Series and Odd Man out Practice Test 3

Question : 7 of 40

Marks: +1, -0

1, 1, 1, 4, 2, ?, 9

Solution:

Concept:

Split the sequence into interleaved subsequences by their positions.

Explanation:

Terms at positions

1,4,7

1,4,9 = 1^2,2^2,3^2

Terms at positions

2,5

1,2

, increasing by

1

Terms at positions

3,6

1,?

, following odd numbers

1,3,5,\ldots

, so

?=3

The completed sequence is

1,1,1,4,2,3,9

Answer:

?=3

, so option A is correct.

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