Question
Three colleagues, M, N, and O, have an average age of
27. Ten years ago, their ages were in the ratio of 4:6:7. What is the average age of M and N today?Solution
Sum of their present ages = 3 × 27 = 81 Sum of their ages before 10 years = 81-30 = 51 Let their ages 10 years ago were 4x, 6x and 7x Then, 4x+6x+7x = 51 17x = 51 x = 3 their ages 10 years ago were 12, 18, 21 present age of M = 12+10 = 22 present age of N = 18+10 = 28 average of present age of M and N = (28+22)/2 = 25
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