The average weight of A, B and C is 45 kg. If the average weight of A and B be 40 kg and that of B and C be 47 kg, then the weight of B is:
Pick one
A) 39 kg  B) 32 kg  C) 33 kg  D) 34 kg  E) None of these
Explanation:   Let A, B, C represent their respective weights. Then, we have:   A + B + C = (45 x 3) = 135 …. (i)   A + B = (40 x 2) = 80 …. (ii)   B + C = (47 x 2) = 94 ….(iii)   Adding (ii) and (iii), we get: A + 2B + C = 174 …. (iv)   Subtracting (i) from (iv), we get : B = 39.   B’s weight = 39 kg.   39 kgnswer: 39 kg
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The average weight of A, B and C is 45 kg. If the average weight of A and B be 40 kg and that of B and C be 47 kg, then the weight of B is: