Paper 1 · Mathematical Reasoning and Aptitude
Find the wrong number in the following sequence: 125, 127, 130, 135, 142, 153, 165
A130
B142
C153
D165 ✓ Correct
Correct answer: (D) 165 — The wrong number is 165, so that is the answer.
Explanation
★The wrong number is 165, so that is the answer.
★Find the differences between the consecutive terms.
★The differences are 2, 3, 5, 7, 11 and then 12.
★The first five differences are the prime numbers 2, 3, 5, 7, 11.
★The next difference should be the prime 13, not 12.
★So the last term should be 153 plus 13, which is 166, making the printed 165 the wrong number.
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