Multiple choice

What will be the sum of father's age and son's age after 5 years? (I) Father's present age is twice the son's present age. (II) After 10 years, the ratio between father's age and son's age will be 12 : 7 (III) 5 years ago, the difference between the father's age and son's age was equal to son's present age.

  1. Only I and II

  2. Only II and III

  3. Any two

  4. Only I and III

  5. All
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let son's present age = S. From I: F = 2S. From II: (F+10)/(S+10) = 12/7, cross-multiply: 7F + 70 = 12S + 120. From III: (F-5) - (S-5) = S, so F - S = S, F = 2S. I and III give same info. Using II with either I or III: 7(2S) + 70 = 12S + 120, 14S + 70 = 12S + 120, 2S = 50, S = 25, F = 50. After 5 years: F+5 + S+5 = 55 + 30 = 85. Any two statements work since I and III are equivalent.

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