Multiple choice

Average weight of P and Q is 16 kg. Average weight of Q and R is 21.5 kg. Average weight of P and R is 25.5 kg. What is the average weight (in kg) of P, Q and R?

  1. 22

  2. 21

  3. 20

  4. 19
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B Correct answer
Explanation

Let P, Q, R be the weights. (P+Q)/2 = 16, so P+Q = 32. (Q+R)/2 = 21.5, so Q+R = 43. (P+R)/2 = 25.5, so P+R = 51. Adding all three equations: 2(P+Q+R) = 32+43+51 = 126, so P+Q+R = 63. Average = (P+Q+R)/3 = 63/3 = 21 kg.

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