A population of middle school students contains 160 sixth graders, 180 seventh graders, and 140 eighth graders. Nine seventh gra
ders were part of a random sample of the population chosen to participate in a survey. For the sample to accurately represent the population, about how many sixth graders should be chosen?
Answer: The middle school has: 160 sixth graders, 180 seventh graders and and 140 eighth graders.
if in the sample of seventh graders were, chosen 9 of them, this is a 9/180= 0.05, or 5% of the total sample of seventh graders.
then, we also need to select a 5% of the total population of sixth graders for the survey, this is 0,05*160= 8, but remember that you need to select this 8 students at random.
the answer is D because since side AB have the same y coordinate then you would have to either subtract or add the x. if one point on x is negative and the other is positive then you would add. but if they were both positive or both negative then you would subtract the x.
