107_8.2_notes_quiz

What is used as the critical value when the population standard deviation is known?

• zα/2

• tα/2

• s

• μ

What happens to the t distribution as the number of degrees of freedom increases?

• It becomes closer to the normal distribution

• It becomes more skewed

• It becomes more uniform

• It becomes less predictable

What is the main objective when constructing a confidence interval for a mean with unknown σ?

• To estimate the value of μ

• To find the exact value of σ

• To determine the sample size

• To calculate the median

What is the relationship between the critical value and the degrees of freedom?

• The critical value depends on the degrees of freedom.

• The critical value is independent of the degrees of freedom.

• The critical value is inversely proportional to the degrees of freedom.

• The critical value is always the same regardless of degrees of freedom.

What is the critical value for a confidence level of 95% with 200 degrees of freedom?

• 1.972

• 2.345

• 2.601

• 2.807

What is the z-value for a 95% confidence level?

• 1.645

• 1.960

• 2.576

• 2.807

What is the critical value for a 99.9% confidence level with df = 60?

• 3.291

• 3.496

• 3.460

• 3.558

In Example 8.5, what is the sample mean of the number of hours spent on the Internet?

• 8.0 hours

• 8.2 hours

• 8.4 hours

• 8.6 hours

What is the margin of error calculated in Example 8.5?

• 1.760

• 2.797

• 1.984

• 2.262

What confidence level is used to construct the interval for the lightbulb lifetimes?

• 95%

• 99%

• 90%

• 85%