Because he divided the population into smaller groups and then randomly sampled each group, he would be using a stratified random sampling procedure.
Answer: c. They would do better charging $15 than $10.
Explanation:
It is given that Max and Maddy total cost of car parking remains the same, that is it does not matter whether they have seven or five cars parked on their lawn. So, since total cost is constant, Max and Maddy's decision would depend on total revenue.

Total revenue from charging, $10 is $70,
Total revenue from charging $15 is $75.
Since, total cost is constant, Max and Maddy will choose to charge $15 since it is giving them $5 more.
This website would not exist. Social lives would improve because everyone would actually hang out with people. We would not be able to get places fast because cars would not be developed.