Final answer:
The water polo team scored a total of 63 goals in the first 9 matches. After scoring 2 goals in the 10th match, their new mean number of goals per match is 6.5.
Step-by-step explanation:
The water polo team's total number of goals for the first 9 matches is calculated by multiplying the mean number of goals per match by the number of matches played. Since the mean number of goals per match is 7, we use the following calculation:
7 goals/match × 9 matches = 63 goals in total
For part b, if the team scores 2 goals in their 10th match, we need to add this to the total and then re-calculate the new mean:
Total goals after 10 matches = 63 + 2 = 65 goals
Mean number of goals after 10 matches = Total goals ÷ Number of matches
Mean = 65 ÷ 10 = 6.5 goals per match