• It increases.

• It decreases.

• It stays the same.

• It depends on the sample mean and standard deviation.

• 1

• 1.25

• 2

• The point estimate cannot be found from this interval.

• 1

• 3

• 4

• The margin of error cannot be found from this interval.

• It increases.

• It decreases.

• It does not change.

Find the value of z* for a confidence level of 80%.

• 1.645

• 0.84

• 1.28

• 1.00

• 1.753

• 2.131

• 2.145

• Cannot be determined because the t interval does not apply.

• 0.572

• 0.586

• 0.594

• Cannot be determined because the t interval does not apply.

• (44.43, 45.57)

• (44.30, 45.70)

• (44.41, 45.59)

• Cannot be determined because the t interval does not apply.

• (86.21, 116.79)

• (86.00, 117.00)

• (83.79, 119.21)

• Cannot be determined because the t interval does not apply.

A random sample of seven 2011 sports cars is taken and their city gas mileage is recorded. The results are as follows:

20 21 25 21 21 23 31.

Assuming the population distribution is normal, what is the point estimate that describes the mean city mpg for 2011 sports cars?

• 20

• 21.2

• 23.1

• 31