Test Index

Series and Odd Man out Practice Test 5

Question : 7 of 40

Marks: +1, -0

7, 32, 258, 882, 2107

Solution:

Concept:

The series follows a pattern of adding squares of numbers ending in 5:

5^2, 15^2, 25^2, 35^2

Explanation:

Start with the first term:

7 + 5^2 = 7 + 25 = 32

Next expected term:

32 + 15^2 = 32 + 225 = 257

, but the series gives

258

Continue checking:

257 + 25^2 = 257 + 625 = 882

Then

882 + 35^2 = 882 + 1225 = 2107

So all later terms match if the third term is

257

, not

258

Answer:

The wrong term is

258

, which should be

257

Correct option: A.

258

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