BRAINLEST!!! 30 points!!!!!!

Directions: Select the correct answer from each drop-down menu.

Brad wanted to determine what type of cereal middle school students in his school preferred.

If Brad only surveyed Ms. Coe's seventh grade math class, the results of the survey would be..

valid or invalid?

If Brad only surveyed every fourth middle school student who rode the school bus in the morning, the results of the survey be

Invalid or valid?


If Brad only survkyed every tenth student on the school roster, the results of the survey be

Valid or invalid?