Sample and Inference

Q1. How many red shirts do you have?

• A) 5 red shirts

• B) 17 red shirts

• C) 40 red shirts

• D) 83 red shirts

There are 400 students at Polly's school. She surveyed a random sample of 80 students to find their favorite hobby. 19 said they like to read. 30 said they like to be with friends. 8 said they like to do crafts. 23 said they like to play sports. Polly infers that doing crafts is the least popular hobby at her school. Refer to the data table. Polly surveys two more samples. Do the results from these samples support the inference made from the first sample?

• Yes, the survey results support the inference that doing crafts is the least popular hobby at Polly's school.

• No, the survey results does not support the inference that doing crafts is the least popular hobby at Polly's school.

The dot plots show how long it took students in Mr. Chauncey's two science classes to finish their science homework last night. Find the means to make an inference about the data.

• The 1st period mean is 35. The 2nd period mean is 38.75. On average, it took students in the 1st period class slightly longer to finish their homework than it did the students in the 2nd period class.

• The 1st period mean is 38.75. The 2nd period mean is 35. On average, it took students in the 1st period class slightly longer to finish their homework than it did the students in the 2nd period class.

• The 1st period mean is 35. The 2nd period mean is 38.75. On average, it took students in the 2nd period class slightly longer to finish their homework than it did the students in the 1st period class.

• The 1st period mean is 38.75. The 2nd period mean is 35. On average, it took students in the 2nd period class slightly longer to finish their homework than it did the students in the 1st period class.

Litzy collects data from a random sample of 7th graders. Out of 40 respondents, 7 attend afterschool programs. Of the 200 7th graders attending Litzy's school, how many would be expected to attend afterschool programs?

• 14 7th graders

• 28 7th graders

• 35 7th graders

• 42 7th graders

The dot plot shows a random sample of the number of fish caught and released by 30 participants during a two-day fishing tournament. Select the inference that can be made based on the data collected.

• On average, most participants caught and released 5 or more fish.

• More participants caught 6 fish than any other number.

• The same participants who caught and released 1 fish the first day caught and released 1 fish on the second day.

• On average, participants caught and released more fish on Day 2.

Brazil asks 7 classmates how many erasers and pens they carry in their bags. The mean number of erasers is 10. The mean number of pens is 4. What inference could Brazil make using this data?

• Most of Brazil's classmates carry more pens than erasers in their bags.

• All of Brazil's classmates carry more erasers than pens in their bags.

• Most of Brazil's classmates carry more erasers than pens in their bags.

• Most of Brazil's classmates carry similar amounts of erasers and pens in their bags.

If you compare the medians of each data set, who spends more time online?

• Seventh graders

• Eight graders

• Both grades spend an equal amount of time online.

• Impossible to determine form the data sets.

A random sample of 50 was taken from a shipment of 12,000 light bulbs. There were 2 broken bulbs in the sample. How many broken bulbs would you expect in the entire shipment?

• 240

• 480

• 2,400

• 4,800

What inference is probably true based on the mean and median of the scores below?

• The Blue team had slightly higher grades, on average.

• The Green team had slightly higher grades, on average.

• The Blue and Green teams had the exact same scores, on average.

• The Blue team’s scores were twice as great as the Green team’s scores.

A town has 35,000 registered voters. A random sample of 500 voters finds that 125 are in favor of a new dog park. How many are likely to vote for the dog park?

• 25

• 125

• 2,625

• 8,750