1a. It is not valid to say that basketball is more popular than football at the school because the poll was taken at a basketball game, where mostly, basketball fans are at.
1b. A better method to get a valid conclusion would be to take the poll during lunch or during a break, that way you can get answers from a good variety of students, where you can get basketball and football fans.
2a. City A: 4
City B: 4
2b. City A: 0.8
City B: 0.8
2c. City A: 3.75
City B: 5.25
3a. Howler Monkey mean: 17
Howler Monkey MAD: 0.75
Spider Monkey mean: 14
Spider Monkey MAD: 0.9375
3c. The howler monkey is on average heavier than the spider monkey. This is because the mean is higher and the MAD is lower. The MAD is the measure of by how much the values in the data set are likely to differ from their mean.