CW - 7.3

Find the critical value and rejection region for the type of t-test with level of significance α and sample size n.

Left-tailed test, α = 0.1, n = 25

• 1.318

• -1.318

• 1.316

• -1.316

Find the critical value and rejection region for the type of t-test with level of significance α and sample size n.

Right-tailed test, α = 0.05, n = 40

• 1.645

• -1.645

• 1.960

• -1.960

Find the critical value and rejection region for the type of t-test with level of significance α and sample size n.
Two-tailed test, α = 0.02, n = 21 

•  $2.528$  

•  $\pm2.528$  

•  $-2.528$  

•  $\pm2.326$  

Find the standardized test statistic t for a sample with n = 12, x = 31.2, s = 2.2, and α = 0.01 if Ho: μ = 30. Round your answer to two decimal places.

• $2.13$

• $1.99$

• $1.89$

• $2.01$

Find the standardized test statistic t for a sample with n = 15, x = 16.25, s = 2.3, and α = 0.05 if Ho: μ ≥ 17.8. Round your answer to two decimal places. 

•  $-2.13$ 

•  $-2.18$ 

•  $-2.87$ 

•  $-2.61$ 

Test the claim about the population mean μ at the level of significance α. Assume the population is normally distributed.

Claim μ = 25; α = 0.01. Sample statistics: x = 25.2, s = 2.6, n = 18

• Reject Ho, at 1% level of significance, there is enough evidence to reject the claim.

• Fail to reject Ho, at 1% level of significance, there is not enough evidence to support the claim.

• Fail to reject Ho, at 1% level of significance, there is not enough evidence to reject the claim.

• Reject Ho, at 1% level of significance, there is enough evidence to support the claim.

Test the claim about the population mean μ at the level of significance α. Assume the population is normally distributed.

Claim μ > 33; α = 0.10.

Sample statistics: x = 34, s = 3, n = 25

• Fail to reject Ho, at 10% level of significance, there is not enough evidence to support the claim.

• Reject Ho, at 10% level of significance, there is enough evidence to reject the claim.

• Fail to reject Ho, at 10% level of significance, there is not enough evidence to reject the claim.

• Reject Ho, at 10% level of significance, there is enough evidence to support the claim.

A principal at a school is worries that his students are below average intelligence. A random sample of 25 students’ IQ scores has a mean of 97. Given that IQ scores are normally distributed with a mean of 100 and standard deviation of 15. Is there enough evidence to reject the principal's claim at a = 0.05?

• Fail to reject Ho, there is not enough evidence to reject the principal's claim.

• Fail to reject Ho, there is not enough evidence to support the principal's claim.

• Reject Ho, there is enough evidence to reject the principal's claim.

• Reject Ho, there is enough evidence to support the principal's claim.

A manufacturer claims that the mean lifetime of its fluorescent bulbs is 1000 hours. A homeowner selects 28 bulbs and finds the mean lifetime to be 1001 hours with a standard deviation of 110 hours. If α = 0.10, test the manufacturerʹs claim using P-values.

• Reject Ho at 10% level of significance, there is enough evidence to reject the claim.

• Fail to reject Ho at 10% level of significance, there is not enough evidence to reject the claim.

• Fail to reject Ho at 10% level of significance, there is not enough evidence to support the claim.

• Reject Ho at 10% level of significance, there is enough evidence to support the claim.

A local school district claims that the number of school days missed by its teachers due to illness is below the national average of μ < 5. A random sample of 28 teachers with a sample mean of 4.3 and standard deviation of 1.32. At α = 0.05, test the districtʹs claim using P-values.

• Fail to reject at 5% level of significance, there is not enough evidence to reject the claim. 

• Reject Ho at 5% level of significance, there is enough evidence to support the claim. 

• Fail to reject at 5% level of significance, there is not enough evidence to support the claim. 

• Reject Ho at 5% level of significance, there is enough evidence to reject the claim.