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 45 kg, then the weight of B is:	Pick one:
A) 31 kg B) 32 kg C) 33 kg D) 35 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 = (45 x 2) = 90 ….(iii)   Adding (ii) and (iii), we get: A + 2B + C = 170 …. (iv)   Subtracting (i) from (iv), we get : B = 35.   B’s weight = 35 kg.   Answer: 35 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 45 kg, then the weight of B is: