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NDA 2 2024 Maths, question 44

Topic: Algebra

Passage · Q43 to Q44

The product of 55 consecutive terms of an AP is 229635229635. The first, second and fifth terms are in GP.

Q44

What is the sum of all five terms?

  1. (a) 6060
  2. (b) 6565
  3. (c) 7575Correct answer
  4. (d) 8080

Solution.

Answer: (c) 7575

  1. From question 43, the terms are 3, 9, 15, 21, 27.
  2. Their sum is 3+9+15+21+27=753 + 9 + 15 + 21 + 27 = 75 (check: their product is 229635).

Trap: The constant AP with d=0d = 0 would give a different sum; as in question 43, the AP is non-constant.