Confidence Intervals Quiz practice set #1

90% confidence interval for a population AVERAGE with n = 35 and an unknown standard deviation.

• ±1.645

• ±1.960

• ±2.000

• ±1.697

90% confidence interval for a population AVERAGE with n = 50 and an unknown standard deviation.

• ±1.675

• ±1.676

• ±1.710

• ±1.650

95% confidence interval for a population AVERAGE with n = 30 and an unknown standard deviation.

• ±2.048

• ±1.960

• ±2.000

• ±2.021

99% confidence interval for a population AVERAGE with n = 60 and an unknown standard deviation.

• ±2.576

• ±2.390

• ±2.660

• ±2.700

85% confidence interval for a population AVERAGE with n = 25 and an unknown standard deviation.

• ±1.340

• ±1.316

• ±1.304

• ±1.315

BOTH critical values for a 90% confidence interval population DEVIATION estimate with n = 20.

• χ² = 30.14, χ² = 10.12

• χ² = 31.41, χ² = 9.59

• χ² = 32.85, χ² = 8.91

• χ² = 28.41, χ² = 10.85

BOTH critical values for a 95% confidence interval population DEVIATION estimate with n = 25.

• χ² = 39.36, χ² = 13.12

• χ² = 40.25, χ² = 14.24

• χ² = 38.88, χ² = 12.65

• χ² = 39.42, χ² = 13.97

BOTH critical values for a 90% confidence interval population DEVIATION estimate with n = 18.

• χ² = 29.88, χ² = 9.67

• χ² = 28.86, χ² = 10.58

• χ² = 27.68, χ² = 10.34

• χ² = 28.34, χ² = 11.01

BOTH critical values for an 88% confidence interval population DEVIATION estimate with n = 15.

• χ² = 24.05, χ² = 8.50

• χ² = 24.91, χ² = 8.71

• χ² = 25.45, χ² = 9.10

• χ² = 23.70, χ² = 8.21

BOTH critical values for a 92% confidence interval population DEVIATION estimate with n = 10.

• χ² = 17.78, χ² = 3.43

• χ² = 17.28, χ² = 3.25

• χ² = 18.31, χ² = 3.10

• χ² = 16.92, χ² = 3.48