Multiple choice

The average weight of 3 persons P, Q, R is 84 kg. Another person who is S joins the group and now the present average of the group becomes 80 kg. If another person T, whose weight is 3 kg more than that of S, replaces P then the average weight of Q, R, S, and T becomes 78 kg. Find the weight of P.

  1. 58 kg.

  2. 61 kg.

  3. 79 kg.

  4. 57 kg.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

P+Q+R = 3×84 = 252kg. When S joins: P+Q+R+S = 4×80 = 320kg, so S = 320-252 = 68kg. T is 3kg more than S, so T = 71kg. New average 78kg for Q,R,S,T means total = 4×78 = 312kg. So Q+R = 312 - (68+71) = 173kg. Then P = 252 - 173 = 79kg.

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