Target Exam

CUET

Subject

General Aptitude Test

Chapter

Quantitative Reasoning

Topic

Permutation & Combination

Question:

Find the sum of 24 terms of the list of numbers whose nth term is given by:

$a_n=3+2n$

Options:

200

172

672

408

Correct Answer:

672

Explanation:

The correct answer is Option (3) → 672

We are asked to find the sum of 24 terms of the sequence:

$a_n = 3 + 2n$

Step 1: First term ($a_1$​) and 24th term ($a_{24}$​)

$a_1 = 3 + 2(1) = 5$

$a_{24} = 3 + 2(24) = 3 + 48 = 51$

Step 2: Sum of first n terms of an arithmetic progression

Formula:

$S_n = \frac{n}{2} (a_1 + a_n)$

$S_{24} = \frac{24}{2} (5 + 51) = 12 \times 56 = 672$