A middle school has 6th grade, 7th grade, and 8th grade teachers. The principal wants to determine what supplies to order for the supply closet. Which of the following represents a random sample of teachers?
a. Surveying all the math teachers
b. Surveying all the teachers who have bus duty
c. Surveying all the teachers who are married
d. Surveying every fifth teacher according to the staff directory on the school website
d. Surveying every fifth teacher according to the staff directory on the school website
A student wants to know which type of pizza high school students prefer. Which of the following options is a good, representative sample of the population?
Asking all the 10th graders in the school
Asking the school principal which type of pizza he prefers
Asking 20 students from each grade level
Asking the students who walk to school