Directions to Solve
In this type of questions, one term in the number series is wrong. Find out the wrong term.
21.
25, 36, 49, 81, 121, 169, 225
A. 36 B. 49
C. 169 D. 225
Answer & Explanation
Answer: Option A
Explanation:
The correct sequence is 52, 72, 92, 112, 132, 152. So, 36 is wrong.
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22.
1, 3, 10, 21, 64, 129, 356, 777
A. 21 B. 129
C. 10 D. 356
Answer & Explanation
Answer: Option D
Explanation:
The correct pattern is x 2 + 1, x 3 + 1, x 2 + 1, x 3 + 1,…..
So, 356 is wrong and must be replaced by (129 x 3 + 1) i.e. 388.
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23.
5, 10, 40, 80, 320, 550, 2560
A. 80 B. 320
C. 550 D. 2560
Answer & Explanation
Answer: Option C
Explanation:
The correct pattern is x 2, x 4, x 2, x 4, …..
So, 550 is wrong and must be replaced by (320 x 2) i.e. 640.
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24.
2, 3, 4, 4, 6, 8, 9, 12, 16
A. 3 B. 6
C. 9 D. 12
Answer & Explanation
Answer: Option C
Explanation:
The given sequence is a combination of three series:
I. 1st, 4th, 7th terms i.e. 2, 4, 9,…..
II. 2nd, 5th, 8th terms i.e. 3, 6, 12,…..
III. 3rd, 6th, 9th terms i.e. 4, 8, 16,…..
In each one of I, II and III, each term is twice the preceding term. So, 9 is wrong and must be replaced by (4 x 2) i.e. 8.
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25.
11, 5, 20, 12, 40, 26, 74, 54
A. 5 B. 20
C. 40 D. 26
Answer & Explanation
Answer: Option C
Explanation:
The given sequence is a combination of two series :
I. 11, 20, 40, 74 and II. 5, 12, 26, 54
The correct pattern in I is + 9, + 18, + 36,…..
So, 40 is wrong and must be replaced by (20 + 18) i.e. 38.