The average weight of A, B, C is 40 kg, the average weight of B, D, E is 42 kg and the weight of F is equal to that of B. What is the average weight of A, B, C, D, E and F?

Here's a brief explanation:

1. From the first statement: The average weight of A, B, C is 40 kg. So, the total weight of A, B, C = 3 * 40 kg = 120 kg. (Equation 1)

2. From the second statement: The average weight of B, D, E is 42 kg. So, the total weight of B, D, E = 3 * 42 kg = 126 kg. (Equation 2)

3. From the third statement: The weight of F is equal to that of B. So, F = B.

4. We need to find the average weight of A, B, C, D, E, F. This means we need to find (A + B + C + D + E + F) / 6.

5. Let's sum the weights of all six individuals: A + B + C + D + E + F We can rewrite this as: (A + B + C) + (D + E) + F

6. Substitute values from our equations: From Equation 1, (A + B + C) = 120 kg. From Equation 2, (D + E) = 126 kg - B. From the third statement, F = B.

7. Substitute these into the total sum: Total sum = 120 kg + (126 kg - B) + B Total sum = 120 kg + 126 kg - B + B Total sum = 120 kg + 126 kg = 246 kg.

8. Now, calculate the average weight of A, B, C, D, E, F: Average = Total sum / Number of people Average = 246 kg / 6 Average = 41 kg.

Therefore, the average weight of A, B, C, D, E and F is 41 kg.

Analyzing the options: A) 40.5 kg - Incorrect. B) 40.8 kg - Incorrect. C) 41 kg - Correct, as calculated. D) Cannot be determined as data is inadequate - Incorrect, as we were able to determine the average.

The final answer is C.