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The ages of father, mother and son are in the ratio 4 ∶ 3 ∶ 1. Daughter’s age is 2/5th of mother’s age and grandmother’s age is twice that…

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The ages of father, mother and son are in the ratio 4 ∶ 3 ∶ 1. Daughter’s age is 2/5th of mother’s age and grandmother’s age is twice that of mother’ age. The average age of the family of five members is 45.6. Find the age of grandmother.
  • A70 years
  • B80 years
  • C90 years
  • D100 years
Answer not set

Discussion 1

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CCommunity
Let the age of father, mother and son be 4x, 3x, x.

Then, Age of daughter = 6x/5

Age of Grandmother = 2 × 3x = 6x

Sum of ages of family = 4x + 3x + x + 6x/5 + 6x = 76x/5

⇒ 76x/5 = 45.6 × 5

⇒ x = 15

⇒ Age of grandmother = 15 × 6 = 90 years