Stats Practice Margain of Error

A recent survey found that 77% of high schoolers use their phones more than 4 hours a day on average. The margin of error was 3%. What is the interval for which we could expect to find the truth of the population?

• 77% - 80%

• 74% - 77%

• 74% - 80%

• 50 million high schoolers - 120 million

Why is a sample of 1000 people better than a sample of 100 people?

• It reduces the margin of error.

• Having more people creates more work.

• More people means that our results are always correct.

A recent survey found that out of 400 random American adults, 89% pay their bills on time. The margin of error in this survey was 2%. What is the interval of values in which the truth is likely found?

• 89% - 91%

• 87% - 89%

• 87% - 91%

• 388 - 402

A research team surveys 200 high schoolers at glenoak. They find that 57% of them drive to school every day. What is the margin of error? (Hint: Use the standard error formula)

• 95%

• 14%

• 7%

• 3%

Determine whether the action would increase or decrease the margin of error:

Increase the sample size

• Margin of error increases

• Margin of error decreases

How do we reduce variability?

• Increase randomness.

• Increase sample size.

• Decrease randomness.

• Decrease sample size.

A research team surveys 1001 adults, asking them how many hours they work per week. What is the margin of error for this survey?

• 3%

• 32%

• 63%

• 9%

Assign each car in a dealership a number and then use a random-number table to select the cars to be inspected. 

• systematic
• random sample
• convenience
• volunteer response

Interview the first 30 students who enter the school in the morning. 

• simple random
• voluntary response
• systematic
• convenience

Disneyland often surveys its guests as they exit a restaurant during their visit. The surveyor stands at the restaurant exit, counts the number of people leaving, and surveys every 25th guest.
This is a form of:

• Random Sample
• Convenience Sampling
• Voluntary Response
• Systematic Sampling