Question
Four years ago, the ages of the father and his son were
in the ratio 7:2. Four years hence, the ages of the father and his son will be in the ratio 9:4. After how many years will the father's age be twice the age of his son?Solution
Let the common ratio be x. Hence, four years ago, the ages of the father and his son were 7x and 2x years. According to the question, (7x+4+4)/ (2x + 4 + 4) = 9:4 28x+ 32 = 18x + 72 10x = 40 x=4 Present age Father = 7x + 4 = 7 x 4 + 4 = 32 Son = 2x + 4 = 2 x 4 + 4 = 12 After P years the father's age will be twice the age of his son. According to the question, 32 + P = 2 x (12 + P) P = 8 year
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