Ten players, one from each weight group, have an average weight of 68 kg, so their total weight is:
\[ 68 \times 10 = 680 \text{ kg} \]When player S leaves, the remaining 9 players have an average of 66.5 kg, so their total weight is:
\[ 66.5 \times 9 = 598.5 \text{ kg} \]S's weight is the difference:
\[ 680 - 598.5 = 81.5 \text{ kg} \]Therefore, the correct answer is Group 9.
After S (81.5 kg) leaves, the remaining 9 players total 598.5 kg. Two new players join and the average of all 11 players rises to 68 kg, so the new total is:
\[ 68 \times 11 = 748 \text{ kg} \]The combined weight of the two new players is:
\[ 748 - 598.5 = 149.5 \text{ kg} \]We need to check which pair of groups CANNOT jointly produce a combined weight of 149.5 kg, using each group's weight range.
Only the pairing of groups 1 and 3 falls short of the required 149.5 kg combined weight.
Therefore, the correct answer is 1 and 3.
This question asks for the average weight of "all the players taken together." Let's check what we actually know versus what's needed to answer this precisely.
Since the exact composition of "all the players" isn't uniquely fixed by the passage, and individual weights within a range aren't pinned to single values, no one figure can be stated with certainty.
Therefore, the correct answer is Cannot be determined.
This question asks which group "contributes most" to the overall average weight. Let's examine what's actually knowable here.
Without exact individual weights, the specific group contributing most to the average cannot be identified with certainty.
Therefore, the correct answer is Cannot be determined.
The two new players' combined weight is 149.5 kg (established earlier). If one of them is from group 4 (weight range 60-64 kg), the other player's weight must fall in the range:
\[ 149.5 - 64 = 85.5 \text{ kg (minimum)} \quad \text{to} \quad 149.5 - 60 = 89.5 \text{ kg (maximum)} \]So the other player's weight lies somewhere between 85.5 kg and 89.5 kg. Let's check which group this fits.
Therefore, the correct answer is Group 10.