number series logical reasoning questions

16.

9 12 11 14 13 16 15
A.     14 13    B.     18 21
C.     14 17    D.     12 13
E.     18 17
Answer & Explanation

Answer: Option E

Explanation:

This is a simple alternating addition and subtraction series. First, 3 is added, then 1 is subtracted, then 3 is added, 1 subtracted, and so on.
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17.

4 8 22 12 16 22 20 24
A.     28 32    B.     28 22
C.     22 28    D.     32 36
E.     22 26
Answer & Explanation

Answer: Option C

Explanation:

This is an alternating repetition series, with a random number, 22, interpolated as every third number into an otherwise simple addition series. In the addition series, 4 is added to each number to arrive at the next number.
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18.

40 40 31 31 22 22 13
A.     13 4    B.     13 5
C.     4 13    D.     9 4
E.     4 4
Answer & Explanation

Answer: Option A

Explanation:

This is a subtraction series with repetition. Each number repeats itself and then decreases by 9.
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19.

1 10 7 20 13 30 19
A.     26 40    B.     29 36
C.     40 25    D.     25 31
E.     40 50
Answer & Explanation

Answer: Option C

Explanation:

Here, every other number follows a different pattern. In the first series, 6 is added to each number to arrive at the next. In the second series, 10 is added to each number to arrive at the next.
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20.

10 20 25 35 40 50 55
A.     70 65    B.     60 70
C.     60 75    D.     60 65
E.     65 70
Answer & Explanation

Answer: Option E

Explanation:

This is an alternating addition series, in which 10 is added, then 5, then 10, and so on.