The average weight of Shubha, Govinda and Reshma is 65 kg. The average weight of Shubha and Govinda together is 63 kg, and the average weight of Govinda and Reshma together is 70 kg. What is the weight (in kg) of Govinda?

Introduction / Context:
This question is very similar to other average problems where individual values must be found from the averages of different groupings. We are given the average weight of three people together and the averages of two person groups within them. From this data, we must determine the weight of Govinda. The problem is solved by converting averages into total sums and then using simple algebra to isolate the unknown weight.

Given Data / Assumptions:

• Let weights be S for Shubha, G for Govinda and R for Reshma.
• Average of S, G and R = 65 kg, so S + G + R = 3 * 65.
• Average of S and G = 63 kg, so S + G = 2 * 63.
• Average of G and R = 70 kg, so G + R = 2 * 70.
• We must find G.

Concept / Approach:
We translate each average into a sum by multiplying by the number of people in that group. This gives three equations in S, G and R. Adding the equations for S + G and G + R produces an expression involving S + 2G + R. We then subtract the equation for S + G + R from this to isolate G. This is a standard approach for such average problems and leads to a quick solution.

Step-by-Step Solution:
Step 1: Convert the given averages into equations. S + G + R = 3 * 65 = 195. S + G = 2 * 63 = 126. G + R = 2 * 70 = 140. Step 2: Add the equations S + G and G + R. (S + G) + (G + R) = 126 + 140. Left side becomes S + 2G + R. Right side is 266. So S + 2G + R = 266. Step 3: Subtract the equation for all three. (S + 2G + R) − (S + G + R) = 266 − 195. Left side simplifies to G; right side is 71. Therefore, G = 71 kg.
Verification / Alternative check:
Find S and R to verify. From S + G = 126, S = 126 − 71 = 55. From G + R = 140, R = 140 − 71 = 69. Check the overall average. S + G + R = 55 + 71 + 69 = 195. Average = 195 / 3 = 65 kg, which matches the given overall average.
Why Other Options Are Wrong:
Weights such as 41, 46, 60 or 88 do not satisfy all three average conditions when substituted into the equations. Each incorrect choice leads to inconsistencies in at least one of the three average relations.
Common Pitfalls:
A common mistake is to attempt solving for S and R first or to confuse the roles of the averages, which can lead to algebraic errors. Another error is miscomputing the products 3 * 65, 2 * 63 or 2 * 70, which directly affects the final value of G.
Final Answer:
Govinda's weight is 71 kilograms.