Confidence Intervals Warm-up

An insurance company checks police records on 600 accidents selected at random. They report a 95% confidence interval of (12.1%, 17.9%) for the population proportion of accidents involving teens.

What is the point estimate?

• 2.9%

• 8.95%

• 15%

• 30%

An insurance company checks police records on 600 accidents selected at random. They report a 95% confidence interval of (12.1%, 17.9%) for the population proportion of accidents involving teens.

What is the margin of error?

• 2.9%

• 8.95%

• 12.1%

• 17.9%

An insurance company checks police records on 600 accidents selected at random. They report a 95% confidence interval of (12.1%, 17.9%) for the population proportion of accidents involving teens.

Which is the correct interpretation of this confidence interval?

• There is a 95% chance of a teen having an accident

• We can expect 95% of teens to have an accident

• We are 95% confident the population proportion of teen accidents lies on this interval

An appliance manufacturer claims that its new refrigerator lasts 15.2 years with a margin of error 2.3 years.

Which is the correct interpretation of the point estimate?

• the number of years one refrigerator lasts

• the number of years a sample of refrigerators manufactured last

• the number of years all refrigerators manufactured last

An appliance manufacturer claims that its new refrigerator lasts 15.2 years with a margin of error 2.3 years.

What is the lower bound of the confidence interval?

• 6.45 years

• 12.9 years

• 17.5 years

• 8.75 years

An appliance manufacturer claims that its new refrigerator lasts 15.2 years with a margin of error 2.3 years.

What is the upper bound of the confidence interval?

• 6.45 years

• 12.9 years

• 17.5 years

• 8.75 years