Question 1

Which of the following Z-scores corresponds to the critical value for a 95% confidence level in a two-tailed test?

Accepted Answer

$$z = \pm 1.96$$

Question 2

A pharmaceutical company wants to test a new drug with a 99% confidence level using a one-tailed test. What is the appropriate critical Z-value?

Accepted Answer

$$z = 2.58$$

Question 3

If a researcher uses a significance level of $$\alpha = 0.10$$ for a two-tailed test, what is the corresponding critical Z-value?

Accepted Answer

$$z = \pm 1.65$$

Question 4

Which of the following best describes the area in the tails for a 90% confidence interval in a two-tailed test?

Accepted Answer

$$\alpha = 0.10$$

Question 5

A psychologist is conducting a one-tailed hypothesis test at the 95% confidence level. What is the critical Z-value she should use?

Accepted Answer

$$z = 1.65$$

Question 6

If the significance level is $$\alpha = 0.05$$ for a two-tailed test, what is the probability in each tail?

Accepted Answer

$$0.025$$

Question 7

A researcher wants to be more confident in her results and increases her confidence level from 90% to 99%. What happens to the critical Z-value for a two-tailed test?

Accepted Answer

It increases from $$z = \pm 1.645 to$$ $$z = \pm 2.575$$

Question 8

Which confidence level corresponds to a critical Z-value of $$\pm 1.28 in a $$two-tailed test?

Accepted Answer

80%

Question 9

A medical researcher is using a one-tailed test with $$\alpha = 0.05. $$What is the critical Z-value?

Accepted Answer

$$z = 1.645$$

Question 10

If a test statistic falls outside the critical Z-value for a two-tailed test at the 99% confidence level, what can you conclude?

Accepted Answer

Reject the null hypothesis at $$\alpha = 0.01$$

Question 11

Which of the following statements is TRUE regarding the relationship between confidence level and significance level ($$\alpha$$)?

Accepted Answer

As the confidence level increases, $$\alpha$$ decreases.

Question 12

A quality control analyst uses a two-tailed test with $$\alpha = 0.20. $$What is the critical Z-value?

Accepted Answer

$$z = \pm 1.28$$

Question 13

For a one-tailed test at the 85% confidence level, what is the critical Z-value?

Accepted Answer

$$z = 1.44$$

Question 14

A researcher is conducting a two-tailed test with a 95% confidence level. What is the total area in both tails combined?

Accepted Answer

$$0.05$$

Question 15

If the critical Z-value for a one-tailed test is $$z = 2.33$$, what is the corresponding significance level ($$\alpha$$)?

Accepted Answer

$$\alpha = 0.01$$

Z-Table Exercises: Critical Values for Confidence Intervals and Hypothesis Testing

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