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IPMAT Indore 2022 - QA (MCQ) Q23 Explanation

Author : Akash Kumar Singh

December 27, 2024

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Explanation:

(b)

Sum of first ‘n’ term of an AP,

Sn = n/2 [2a + (n−1)d]

Sum of first 15 terms =15/2 [2a+14d] = 200

⇒ a + 7d = 40/3 -----(I)

Sum of next 15 terms = Sum of first 30 terms – Sum of first 15 terms

= 30/2 [2a + 29d] −15/2 [2a+14d] = 350

⇒ 4a + 58d − 2a − 14d =140/3

⇒ 2a + 44d = 140/3 ⇒ a + 32d =70/3 --------(2)

Solving equation (1) and equation (2), we get d = 2/3