The average weight of X, Y and Z is 35 kg. If the average weight of X and Y is 33 kg and that of Y and Z is 29 kg, then what is the weight (in kg) of Y?

Let weight of X, Y and Z be $$x,y,z$$ kg respectively.

Average weight of X, Y and Z = $$\frac{(x+y+z)}{3}=35$$

=> $$x+y+z=35\times3=105$$ ------------(i)

Also, average weight of X and Y = $$\frac{(x+y)}{2}=33$$

=> $$x+y=66$$  ------------(ii)

Similarly, $$y+z=58$$ -----------(iii)

Adding equations (ii) and (iii), => $$x+2y+z=124$$ ----------(iv)

Subtracting equation (i) from (iv), we get :

=> $$y=124-105=19$$

$$\therefore$$ Weight of Y = 19 kg

=> Ans - (B)