Let's define the variables:
- B represents the number of gymnasts who achieved better scores in Round 2 compared to Round 1.
- W represents the number of gymnasts who had worse scores in Round 2 compared to Round 1.
- S represents the number of gymnasts who received the same score in both rounds.
We are given the following information:
1. B + W + S = 38 (the total number of gymnasts).
2. B = 1.25W (the number of gymnasts with better scores is 25% greater than those with worse scores).
3. S = 2B (the number of gymnasts with the same score is twice the number of gymnasts with better scores).
Using the second piece of information, we can express B in terms of W:
B = 1.25W
Using the third piece of information, we can express S in terms of B:
S = 2B
Now, substitute B from the second piece of information into the third piece of information:
S = 2(1.25W)
S = 2.5W
We now have:
B = 1.25W
S = 2.5W
Substitute these expressions for B and S back into the total number of gymnasts equation:
B + W + S = 38
1.25W + W + 2.5W = 38
4.75W = 38
Solve for W:
W = 38 / 4.75
W = 8
Now, find B and S:
B = 1.25W
B = 1.25 * 8
B = 10
S = 2.5W
S = 2.5 * 8
S = 20
Thus, the number of gymnasts who had better scores in Round 2 compared to Round 1 is B:
B = 10
IMO. C