Answer:
Null hypothesis: 
Alternative hypothesis: 
The alternative hypothesis for this case is that at least one mean is different from the others.
And the best method for this case is an ANOVA test.
Step-by-step explanation:
For this case we wnat to test if all the mean length of all face-to-face meetings and the mean length of all Zoom meetings are the same. So then the system of hypothesis are:
Null hypothesis: 
Alternative hypothesis: 
The alternative hypothesis for this case is that at least one mean is different from the others.
And the best method for this case is an ANOVA test.
60% choose band......40% choose chorus
30% who are taking band are girls......30% of 60% is (0.3 * 0.6) = 0.18 or 18%..so 18% are girls.
70% who take chorus are girls....70% of 40% is (0.7 * 0.4) = 0.28 or 28%...so 28% are girls.
18% + 28% = 46%....so a total of 46% taking band and chorus are girls.....so that leaves (100% - 46%) = 54% ( or 0.54) are boys
You see 25 squares because length×height=area, and the area of a figure is how many of something is in it.