Aptitude - Odd Man Out and Series

Exercise :: Odd Man Out and Series - Missing No.

Insert the missing number.
11. 

5, 10, 13, 26, 29, 58, 61, (....)

A. 122
B. 64
C. 125
D. 128

Answer: Option A

Explanation:

Numbers are alternatively multiplied by 2 and increased by 3.

So, the missing number = 61 x 2 = 122.


12. 

15, 31, 63, 127, 255, (....)

A. 513
B. 511
C. 517
D. 523

Answer: Option B

Explanation:

Each number is double the preceding one plus 1.

So, the next number is (255 x 2) + 1 = 511.


13. 

1, 8, 27, 64, 125, 216, (....)

A. 354
B. 343
C. 392
D. 245

Answer: Option B

Explanation:

Numbers are 13, 23, 33, 43, 53, 63.

So, the missing number is 73 = 343.


14. 

3, 7, 6, 5, 9, 3, 12, 1, 15, (....)

A. 18
B. 13
C. -1
D. 3

Answer: Option C

Explanation:

There are two series, beginning respectively with 3 and 7. In one 3 is added and in another 2 is subtracted.

The next number is 1 - 2 = -1.


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