Question

    The average of a, b and c is 8 less than d. If the average of a, b, c and d is 42, and the average of b and c is 43. then find the average of (a-6) and (d+2).

    A 56 Correct Answer Incorrect Answer
    B 51 Correct Answer Incorrect Answer
    C 75 Correct Answer Incorrect Answer
    D 49 Correct Answer Incorrect Answer

    Solution

    ATQ, (a+b+c)/3 = d-8 a+b+c = 3d-24 a+b+c+d=42×4=168 3d-24+d = 168 4d=168+24 ∴ d=192/4 d =48 and again, b+c = 2 × 43 b+c = 86 a + b + c = 3d-24 = 144-24 =120 a = 120-86 = 34 average of (a-6) and (d+2) = ½ [(68-6) + (48+2)] = 112/2 = 5 6

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