Random Samples and Bias

A townhouse community of 250 residents wants to determine if installing a new playground will be a good idea.  Which group of residents would be the best sample to use for a survey that is designed to gather information about the opinions of all the townhouse community?

• Randomly choosing 50 residents without children.

• Randomly choosing 50 residents with children.

• Randomly choosing 50 residents by drawing house numbers from all the house numbers in the community.

• Randomly choosing 50 residents by drawing house numbers from the odd numbered houses in the community.

Which of the following is an example of a biased sample.  Select ALL that apply.

• Marcie wants to find out the favorite type of ice cream for her 7th grade class.  She puts all of their names in a bag, draws 15 names from the bag and surveys those students.

• Charlie wants to find out the favorite car of the people in his small town.  He surveys 25 people at the local Ford dealership.

• Lucy wants to find out if the boys in her math class are smarter than the girls.  She randomly chooses 10 girls and asks what they think.

• Patty wants to find out who likes to kayak on the weekends in her 8th grade class.  During 8th grade lunch she randomly surveys 50 students by handing out slips of paper with her survey question printed on them.  She places a collection basket at the exit to the cafeteria for the students to return the completed slips.

Linus wants to find out what type of music his classmates enjoy most.  Determine which of the survey questions may not be biased.  Choose the TWO that apply.

• Is rock your favorite kind of music?

• What is your favorite kind of music?

• Country is the best type of music, don’t you think?

• If you could choose any music to listen to, what would you choose?

A recent shipment of 2,500 iPhones at the local Best Buy store needed to be checked for manufacturing defects.  The manager chose 25 at random and found 4 to be defective.  (Do not type any words in your answer)

A random sample of cats at the SPCA shows that 25 out of the 40 cats are orange.  There are a total of 800 cats at all the animal shelters in the area.  

Using this information, predict the number of orange cats.

(Do not type any words in your answer.)

A random sample of 900 passengers boarding a plane were asked if they had flown before.

132 Have flown before

18 Have NOT flown before

Write a proportion that can be used to determine how many passengers have probably not flown before. 

A random sample of 900 passengers boarding a plane were asked if they had flown before.

132 Have flown before

18 Have NOT flown before

Based on the survey results, how many passengers have probably not flown before?