Grade 7 | Unit 8: Probability and Sampling | End-of-Unit Assessment (B)

Elena would like to know the average speed that people drive on her street. She tracks the speed of 30 random cars that drive through with a speedometer. The mean of Elena’s sample is 30 miles per hour, and the MAD (mean absolute deviation) is 3. Select all the true statements.

• Elena would be more likely to get an accurate estimate of the mean speed of the population by sampling 60 cars instead of sampling 30 cars.

• The median speed of the sample must be between 25 and 35 miles per hour.

• Another random sample of 30 cars is likely to have a mean between 24 and 36 miles per hour.

• The mean speed of these 30 cars is likely to be the same as the mean speed of a second sample of 30 cars.

• The mean speed of these random 30 cars is likely to be the same as the mean of all cars that drive in a residential area.

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7.SP.A.1

7.SP.A.2

Here is a dot plot showing how many books are read by each student per month. Which of the following is a representative sample of the population?

• 
• B

• C

• D

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7.SP.A.1

For which data set would the mean be a good way to describe the center of the data?

• white, blue, white, white, red

• a dot plot

• 79, 80, 80, 88, 90, 92, 94

• a histogram

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7.SP.A.2

7.SP.B.4

A school plans to start selling snacks at their basketball games. They want to know which snacks would be most popular. What is the population for the school's question? Give an example of a sample the school could use to help answer their question.

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7.SP.A.1

Two different classes took a survey to determine the number of minutes spent on homework one evening. Here is a box plot showing the results from Class A: Here are the results from Class B: In which class did students spend less time on their homework? Which class had less variability in the amount of time spent on homework?

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7.SP.B.4

The school bookstore surveyed a random sample of 10 students on whether they prefer to use a metal or plastic pen. Here were the results: metal, metal, metal, plastic, plastic, metal, plastic, plastic, plastic, plastic. a. Estimate the proportion of all students that prefer to use a metal pen. b. The next day, the bookstore surveyed another random sample of 10 students and found that 20% of them preferred plastic pens. Should the bookstore believe that the results from the two days reasonably represent the preferences of the student population, or should the bookstore gather more data? Explain how you know.

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7.SP.A.2

7.SP.C.6

Students are conducting a class experiment to see if there is a meaningful difference between two groups of plants that have begun to sprout leaves. The teacher randomly selects 8 plants from each group and counts the number of leaves on each plant. Group A: 2, 2, 3, 3, 5, 5, 5, 7. Group B: 10, 9, 7, 8, 10, 12, 14, 10. Is there a meaningful difference between the two groups? Show all calculations that lead to your answer.

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7.SP.B.3

7.SP.B.4