Explanation:

Alright, here’s how I would break down your question and the statements:

- We know the average weight is 50 kg. The question is, can we find out exactly how many students there are?

Statement I

- The heaviest is 60 kg, the lightest is 40 kg.

- That gives us a range of weights, but not how many students. The average could be made with almost any number of students, as long as their weights sum correctly.

- Not enough to find the number.

Statement II

- Removing the heaviest and lightest does not change the average.

- That’s unusual, but it only tells us something about how the outliers balance each other—not the class size.

- Still not enough to solve for the number.

Using Both Together

- Put both facts together: you still don’t know the class size.

- All we have is average, and info about the ends of the weight range, but the average formula could work for different class sizes.

- Try plugging in numbers and you’ll see you can’t pin down a single answer.

Options:

1. Only one statement works — clearly not the case.

2. Either statement works — same problem.

3. Together they work — still not true.

4. Not even both together work — Yep, that’s it.

Correct Answer:

Option: 4