Question

The average weight of A, B and C is $45kg$. If the average weight of A and B be $40kg$ and that of B and C be $43kg$, then the weight of B is:

• A. $17kg$
• B. $20kg$
• C. $26kg$
• D. $31kg$

Answer 1

Answer: (D)

$31kg$

Let A, B, C represent their respective weights. Then, we have:
$A+B+C=(45\times 3)=135.....\left(i\right)$
$A+B=(40\times 2)=80.....\left(ii\right)$
$B+C=(43\times 2)=86.....\left(iii\right)$
Adding (ii) and (iii), we get: $A+2B+C=166....\left(iv\right)$
Subtracting (i) from (iv), we get: $B=31$.
$\therefore B^{\prime }sweight=31kg$.