JEE Main 2024 Mathematics question
Let 3, a, b, c be in A.P. and 3, a − 1, b + 1, c + 9 be in G.P. Then, the arithmetic mean of a, b and c is:
Answer: (C)
Solution
With common difference d: (2 + d)² = 3(4 + 2d) ⇒ d = 4 (d = −2 gives a zero term); a, b, c = 7, 11, 15 with mean 11.