Number Series, Coding and DecodingPYQ Sept 25Question 4444 of 217

In the following series, one term is wrong. Find out the wrong term. 48, 50, 82, 170, 290

A48

B50

C82

D170

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Correct Answer

✅ Option a — 48

Let us analyze the terms of the series:

\displaystyle 48, 50, 82, 170, 290

. Each term except the first can be written in the form

\displaystyle k^2 + 1

: -

\displaystyle 50 = 7^2 + 1

\displaystyle 82 = 9^2 + 1

\displaystyle 170 = 13^2 + 1

\displaystyle 290 = 17^2 + 1

The first term is

\displaystyle 48 = 7^2 - 1

, which is of the form

\displaystyle k^2 - 1

. To fit the general pattern of

\displaystyle k^2 + 1

(with base sequence being primes or similar starting from 5:

\displaystyle 5^2+1 = 26

), the first term should have been 26 instead of 48. Therefore, 48 is the wrong term in the series.
Hence, **Option A** is the correct answer.

Paper

Paper 3: Quantitative Aptitude

Weightage

5 Marks

Key Topics

Number series, Coding & Decoding, Odd man out

This chapter covers Number series, Coding & Decoding, Odd man out and is part of Paper 3: Quantitative Aptitude in the CA Foundation exam.

Exam Strategy Tip

This topic carries 5 Marks weightage. Focus on understanding core concepts rather than memorizing.

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