In a family of 4, the mean age is 30 years. When the grandmother comes to live with them, the mean age of the 5 members becomes 36 years. How old is the grandmother (in years)?

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Accepted Answer

60. Sum of 4 ages = 120; sum of 5 ages = 180. Grandmother's age = 180 − 120 = 60 years.

In a family of 4, the mean age is 30 years. When the grandmother comes to live with them, the mean age of the 5 members becomes 36 years. How old is the grandmother (in years)?

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