A group of three friends, K, L and M, are sitting in a cafe. Their average age is 24 years. Another friend 'N' joins the group and the new average age of the group becomes 23 years. If another friend 'R', whose age is 2 years more than that of 'N', replaces 'K', then the average age of L, M, N and R become 22.5 years. What is the age of K?
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e 24 years.
| Understanding |
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The average age of K, L and M = 24 yrs Sum(K + L + M) = 24 × 3 = 72 -------(1) The average age of K, L, M and N = 23 yrs Sum (K + L + M + N) = 23 × 4 = 92 ------(2) From above equations N = 20 yrs Age of R = N + 2 = 22 yrs From equation (2); L + M + N = 92 - K According to the question; (L + M + N + R) ÷ 4 = 22.5 ⇒ (92 - K + R) ÷ 4 = 22.5 ⇒ (92 - K + 22) = 90 ⇒ K = 24 yrs Hence, option 1 is the correct answer. |