Compare 2 Populations Study Guide

Andre wants to know how teachers in the local school district generally feel about a proposed plan to change from five day weeks to four day weeks. Which of the following methods will produce a representative sample and therefore provide valid inferences?

• Survey all of the teachers who have publicly protested or supported the proposal.

• Survey the first 50 teachers who arrive at Andre’s school in the morning.

• Survey a random sample of 50 teachers within the school district.

• Survey a random sample of 50 teachers and parents of kids within the school district.

Chloe tries to predict what store in the mall is most popular among students in her

school. Which method is most likely to produce a representative sample?

• Asking her best friends.

• Asking members of her softball team.

• Asking one student from each class.

• Asking the kids at her lunch table.

A factory manager conducted tests on a random sample of 200 products. Of the

products tested, 6 were found to have defects. Based on this information, how many products in a batch of 5,000 are likely to be defective?

• 6

• 200

• 160

• 150

Miko took a survey of the students in her grade to see how many are likely to join a book club if she starts one. She surveyed 60 students, and fifteen said they would join. If there are 400 students in her grade, how many students might Miko expect to join the club?

• 100

• 125

• 150

• 175

What does the interquartile range represent?

• The average

• The median

• The difference between the upper and lower quartiles

• The difference between the maximum and minimum values

Ms. Lopez made the box-and-whiskers plot of the student scores on the most recent math test. What percentage of students received a 80 or above on their test?

• 25%

• 50%

• 75%

• 100%

Based on the box plots, for which city do you predict cooler temperatures?

• Atlanta

• Dallas

• Both Cities

• Neither City

The box plots compare the speed of drivers on a busy highway before and after the Department of Transportation placed an additional 55 mph speed limit sign.

What conclusion can be drawn from the placement of the additional sign?

• There was less variability in speeds before the sign.

• The drivers were still speeding so the sign did not make a difference.

• Before the sign, half of the data was above the speed limit; after the sign, half of the data was below the speed limit.

• 75% of the data overlaps, so the sign did not make a difference.

The cost of flights offered by two different airlines are compared in the box and whisker plot. Which of the following statements is true?

• The upper quartile of Airline A is the same as the minimum of Airline B.

• The upper quartile of Airline A is the same as the lower quartile of Airline B.

• The median of Airline A is greater than the median of Airline B.

• The minimum of Airline A is greater than the minimum of Airline B.

These boxplots show the number of cookies eaten by students in our class. Based on

the boxplots, which of the following statements about the cookies eaten is incorrect?

• 50% of the boys ate more cookies than all of the girls,

• All of the boys ate at least one cookie.

• Half of the girls ate two or more cookies.

• Just 25% of the girls ate three or less cookies.