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

Elena would like to know the average height of seventh graders in her school district. She measures the heights of everyone in a random sample of 20 students. The mean height of Elena’s sample is 61 inches, and the MAD (mean absolute deviation) is 2 inches. Select all the true statements.

• The median height of the sample must be between 59 and 63 inches.

• Another random sample of 20 students is likely to have a mean between 57 and 65 inches.

• The mean height of these 20 students is likely to be the same as the mean height of all students in the district.

• The mean height of these 20 students is likely to be the same as the mean height of a second random sample of 20 students.

• Elena would be more likely to get an accurate estimate of the mean height of the population by sampling 40 people instead of sampling 20 people.

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7.SP.A.1

7.SP.A.2

Here is a dot plot showing how much time customers spent in a store, rounded to the nearest five minutes. Which of the following is a representative sample of this population?

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• 
• C

• D

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7.SP.A.1

Select all of the data sets for which you would use the mean to describe the center of the data.

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• 
• 
• D

• E

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7.SP.A.2

7.SP.B.4

An administrator of a large middle school is installing some vending machines in the school. She wants to know what type of machine would be most popular. What is the population for the administrator’s question? Give an example of a sample the administrator could use to help answer her question.

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7.SP.A.1

Two classes of students took an exam. Here is a list of the scores in Class A: 65, 70, 70, 80, 80, 85, 85, 85, 90, 90, 100. Here is a box plot that shows the scores in Class B. Which class had better overall results on the exam? Which class had greater variability in the results?

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7.SP.B.4

A store owner asks each person to write “Yes” or “No” on a slip of paper as they leave, secretly writing down whether they were happy with their experience. At the end of the day, the owner selects 12 slips at random and looks at them. These were the results: yes, yes, yes, no, yes, no, yes, yes, no, yes, no, yes. Estimate the proportion of all shoppers who were happy with their experience that day. On a different day, the owner found that 25% of the 12 selected slips were marked “Yes.” Should the store owner believe that these two results reasonably represent the overall proportion of happy shoppers, or should the owner gather more data? Explain how you know.

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7.SP.A.2

7.SP.C.6

A scientist wants to know if there is a meaningful difference between two groups of gels that grow bacteria. He randomly selects six gels from each group, and counts the number of bacteria spots on each gel: Group A: 9, 12, 13, 13, 14, 17; Group B: 8, 6, 5, 8, 13, 8. 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