Making Inferences from a Sample of Data

Jon finds a box of 350 postcards. He selects a random sample of 75 postcards and finds that 27 already have a stamp on them. Predict the total number of postcards in the box with stamps on them.

• 9,450 postcards

• 126 postcards

• 13 postcards

• 5 postcards

Zoie completes a report by asking 70 students across campus. She found that 48% of CIAA students do not wash their hands after using the bathroom. What is the population of her survey?

• the bathroom

• CIAA students

• 48% of students

Making a conclusion by interpreting data is called making a(n) ________________________.

• Inference

• population

• random sample

• sample

• valid inference

A(n) _______________________ is one that is true about a population based on a representative sample.

• population

• random sample

• sample

• valid inference

The dot plots show the number of calls that two radio stations receive each day for a ten-day period. The two shows are shown at the same time. Which of the following inferences based on the median values is valid?

• The radio shows receive similar amounts of calls.

• Radio Show 1 generally receives more calls.

• Radio Show 2 generally receives more calls.

Margo wants to convince her father to change her curfew from 9 P.M. to 10 P.M. She gathers data on curfew times from a random sample of students at her middle school. Can Margo use these data to present a valid inference that will convince her father? Explain.

• Yes; Most students have a curfew of 10 P.M. or later.

• Yes; More students have a curfew of 9 P.M. than any other time.

• No; Most students have a curfew of 9 P.M. or earlier.

• No; More students have a curfew of 10 P.M. or 11 P.M. than 8 P.M.

True or False: Random samples can represent the population

• True

• False

Ten fourth-grade girls and ten seventh-grade girls were randomly selected. Their heights, in inches, are recorded below. 4th Grade 56, 47, 54, 51, 53, 58, 48, 54, 46, 53 7th Grade 57, 58, 60, 64, 62, 52, 57, 60, 65, 55 Find the range of both classes heights' and make an inference about them.

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Four fourth-grade girls and four seventh-grade girls were randomly selected. Their heights, in inches, are recorded below. 4th Grade 56, 47, 54, 51 7th Grade 57, 58, 60, 64 Find the range for both classes and make an inference about the range of scores.

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Four fourth-grade girls and four seventh-grade girls were randomly selected. Their heights, in inches, are recorded below.

4th Grade
56, 47, 54, 51

7th Grade
57, 58, 60, 64

Which grade has the highest mean?

• 4th Grade

• 7th Grade