Students in a college statistics class want to conduct a survey to determine the percentage of students in the school who are willing to pay a fee for participating in extracurricular activities. thirty students are randomly selected to complete the survey from each of the freshman, sophomore, junior, and senior classes. this plan is an example of which type of sampling?
a. convenience sampling
b stratified sampling
c. simple random sampling
d. a cluster sampling

d.a cluster sampling

Step-by-step explanation:

This plan exemplifies Cluster sampling. It is a sampling method where populations are placed into different separate groups like here into freshman, sophomore, junior, and senior classes. A random sample of these groups is then selected as here thirty students selected from each group to represent a specific population. It is usually used in that type of research when there is no possible way to find information about a population as a whole.

just take the area of the square and then the area of the circle then subtract the circle area from the squares area

step-by-step explanation: