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    Question

    The average age of a group of

    five friends is 78 years. If a friend, aged 48 years, is replaced by another friend, then the average age of each friend in the group will increase by 4 years. Find the age of the friend who was replaced.
    A 78 yrs Correct Answer Incorrect Answer
    B 68 yrs Correct Answer Incorrect Answer
    C 58 yrs Correct Answer Incorrect Answer
    D 55 yrs Correct Answer Incorrect Answer

    Solution

    ATQ,

    Sum of the ages of 5 friends, initially = 5 X 78 = 390 years Let the age of the new friend who joined the group = 'y' years Therefore, 390 - 48 + y = 5 X (78 + 4) Or, 'y' = 410 - 342 = 68 Therefore, age of the new friend = 68 years Alternate Solution Age of the new friend = age of the friend replaced + increase in average age X number of friends So, age of the new friend = 48 + 5 X 4 = 48 + 20 = 68 years

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