Number Series, Coding and DecodingMCQMTP May 19 Series IIQuestion 2043 of 217
All Questions

Find the missing number of the series 22,24,28,?,52,84\displaystyle 22, 24, 28, ?, 52, 84

Options

A31
B38
C42
D46
For any discrepancies in this question, email contact@cadada.in

Correct Answer

✅ Option b — 38

All Options:

  • A31
  • B38
  • C42
  • D46

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Detailed Solution & Explanation

We are given the series: 22,24,28,?,52,84\displaystyle 22, 24, 28, ?, 52, 84
Let's find the differences between consecutive terms:
- 24−22=2\displaystyle 24 - 22 = 2
- 28−24=4\displaystyle 28 - 24 = 4
If the differences are doubling each time (2,4,8,16,32\displaystyle 2, 4, 8, 16, 32):
- Next difference = 8  ⟹  \displaystyle 8 \implies missing term = 28+8=36\displaystyle 28 + 8 = 36.
- Next difference = 16  ⟹  \displaystyle 16 \implies next term = 36+16=52\displaystyle 36 + 16 = 52. (Matches!)
- Next difference = 32  ⟹  \displaystyle 32 \implies next term = 52+32=84\displaystyle 52 + 32 = 84. (Matches!)
This mathematical proof confirms that the correct missing number is 36\displaystyle 36.

**Discrepancy Note:**
The textbook's multiple-choice options are: A (31), B (38), C (42), D (46).
The textbook's answer key contains a typographical error, incorrectly marking Option B (38) as correct. This is a common misprint where 36\displaystyle 36 was printed or keyed as 38\displaystyle 38. Mathematically, the correct value is 36\displaystyle 36.
Hence, **Option B** is the correct answer (in accordance with the textbook's key, though mathematically the correct value is 36\displaystyle 36).

About This Chapter: Number Series, Coding and Decoding

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.

View Official ICAI Syllabus

Exam Strategy Tip

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

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