The average weight of Shivam, Rupesh and Mandar is 46 kg. If the average weight of Shivam and Rupesh be 39 kg and that of Rupesh and Mandar be 48 kg, then the weight of Rupesh (in kg) is:

Correct option is A

Given:

Average weight of Shivam, Rupesh, and Mandar = 46 kg

Average weight of Shivam and Rupesh = 39 kg

Average weight of Rupesh and Mandar = 48 kg

Formula Used:

Average = $$\frac{\text{Sum of observations}}{\text{Number of observations}}$$​​

Solution:

Let weights be:

Shivam = S, Rupesh = R, Mandar = M

From the given:

​$$\frac{S + R + M}{3} = 46 \Rightarrow S + R + M = 138.......(1) \\ \ \\\frac{S + R}{2} = 39 \Rightarrow S + R = 78 .......(2) \\ \ \\\frac{R + M}{2} = 48 \Rightarrow R + M = 96 ........(3)$$​​

Subtract (2) from (1):

(S + R + M) - (S + R) = 138 - 78

M = 60

Now from (3):

R + M = 96

R + 60 = 96

R = 36 kg