(FOR -F/G) - Inferences and Random Sampling May 16, 24

Trinity asked a random sample of 50 students at her school if they brought lunch from home today. If 30 answered “yes,” about what percent of students at Trinity’s school brought lunch from home today?

• 15%

• 30%

• 50%

• 60%

A representative sample of 80 customers in a clothing store was surveyed about how they paid for their purchases. The table shows the responses. Based on the results, which of the following are valid inferences. Select all that apply.

• Tomorrow, 8 out of the first 80 customers will for sure pay with a gift card.

• In a group of 40 customers, it is expected that about 10 will pay with cash.

• About 0.3, or 30%, of all the store's customers will pay with a credit card.

• A sample of 100 customers would provide less reliable data.

Tags

CCSS.7.SP.A.2

Yadira wanted to estimate the mean number of words per page in a 180-page book she is reading. Which if these sampling methods gives the best estimate of the mean word count per page in the book?

• Count the words on one randomly chosen page.

• Calculate the mean word count for a sample consisting of the pages with pictures.

• Calculate the mean word count for a sample of 20 pages selected by choosing every 9th page.

• Calculate the mean word count for a sample consisting of the 10 pages that appear to have the most words.

Tags

CCSS.7.SP.A.2

Using your inference skills and proportional reasoning, predict the number of purple jellybeans in a bag of 200 total jellybeans if a random sample of 25 resulted in 4 purple jellybeans. I predict there will be _________ purple jellybeans.

Tags

CCSS.7.SP.A.2

Which size random sample is likely to provide the most trustworthy results?

• 5

• 10

• 30

• There is no difference.

Tags

CCSS.7.SP.A.1

CCSS.HSS.IC.A.1

A researcher asked five of his doctor friends if they thought the new Brand X medicine that he developed was effective. Four responded "yes." The researcher used the results to write a TV advertisement claiming that "4 out of 5 doctors prefer Brand X medicine." Is this a valid inference? Explain.

• No, because the doctors asked are not a representative sample of the population of doctors.

• No, because 4 doctors said yes out of 9 who were asked.

• Yes, because the doctors asked are a representative sample of the population of doctors.

• Yes, because 4 doctors said yes out of the 5 who were asked.

Tags

CCSS.RI.7.1

CCSS.RI.7.8

CCSS.RI.8.1

CCSS.RL.7.1

CCSS.RL.8.1

An entire group of objects - people, animals, plants - from which data can be collected.

• population

• sample

• representative sample

• random sample

Tags

CCSS.7.SP.A.1

CCSS.HSS.IC.A.1

_______ is a part of a group being surveyed.

• Sample
• Population
• Random Sample
• Quartile

Tags

CCSS.7.SP.A.1

CCSS.HSS.IC.A.1

What inference can be made about the populations based on Paisley's data?

• young teachers drive trucks

• SUVs are driven by teachers with families

• most teachers drive sedans

• fewer teachers drive sedans than SUVs

Tags

CCSS.7.SP.A.2

Harry collects data from a random sample of seventh-graders. Out of 25 respondents, 10 ride the bus to school. Out of 150 seventh-graders who attend Harry's school, how many would be expected to ride the bus to school?

• 40 seventh-graders

• 50 seventh-graders

• 60 seventh-graders

• 90 seventh-graders

Tags

CCSS.7.SP.A.2