As the confidence level increases, the confidence interval __________________.

• Decreases

• Increases

• Stays the same

For a 90% confidence interval, what is the area under the RIGHT tail?

• 0.10

• 0.005

• 0.05

• 0.025

For a 95% confidence interval, what is the area under the LEFT tail?

• 0.05

• 0.10

• 0.025

• 0.005

For a 99% confidence interval, what is the combined area under the BOTH tails?

• 0.005

• 0.10

• 0.01

• 0.05

The z-score corresponding to a 90% confidence interval is:

• ± 1.96

• ± 1.65

• ± 2.58

• ± 1.90

The z-score corresponding with a 99% confidence interval is:

• ± 1.65

• ± 1.96

• ± 2.58

• ± 1.99

The z-score corresponding to a 95% confidence interval is:

• ± 1.96

• ± 2.58

• ± 1.65

• ± 1.75

Find the 95% confidence interval using the following information: (round to 2 decimal places)
 $\overline{x}$  = 20, σ = 3, n = 36

• 18.97 < u < 20.23

• 19.11 < u < 19.89

• 19.05 < u < 20.95

• 19.02 < u < 20.98

Find the 99% confidence interval using the following information: (round to 2 decimal places)
 $\overline{x}$ = 25, σ = 3, n = 36

• 23.71 < u < 26.29

• 23.56 < u < 26.44

• 23.01 < u < 24.99

• 23.80 < u < 26.20

Find the 90% confidence interval using the following information: (round to 2 decimal places)
 $\overline{x}$ = 30, σ = 3, n = 25

• 29.10 < u < 30.90

• 29.01 < u < 30.99

• 29.15 < u < 30.85

• 28.99 < u < 31.01