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    Question

    The average age of a group of 70 students is 14 years.

    If three students whose ages are 22years, 20years, ________ years is replaced with three new student whose ages are 19 years, ______ years, and 32 years, then the new average age is increased by 0.4 years. I. 17, 36 II. 22, 41 III. 15, 34
    A Only I Correct Answer Incorrect Answer
    B Only II, III Correct Answer Incorrect Answer
    C Only I, III Correct Answer Incorrect Answer
    D Only I, II Correct Answer Incorrect Answer
    E All I, II, III Correct Answer Incorrect Answer

    Solution

    The average age increased by 0.4 years. So, the difference of sum of ages of new student to the age of old student = 70*0.4 = 28 years (19+32+__x___) - (20+22+__y__) = 28 (x-y) + (51-42) = 28 x-y = 19 So, option I, II, and III all satisfy the above relation Hence, all three will be the answer.

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