Statistics & Probability ST2

It refers to the region where the value of the test statistic lies for which we will reject the null hypothesis.

• acceptance region

• critical value

• critical region

• probability

For a 𝑧−test distribution with 𝛼=0.01, which of the following is the rejection region for a two-tailed test?

• z < −2.575 or z > 2.575

• z < −1.96 or z >1.96

• z <−1.645 or z >1.645

• z < −2.33 or z >2.33

For a 𝑧−test distribution with 𝛼=0.05, which of the following is the rejection region for a two-tailed test?

• z < −2.575 or z >2.575

• z < −1.96 or z >1.96

• z < −1.645 or z >1.645

• z < −2.33 or z >2.33

For a 𝑧−test distribution with 𝛼=0.10, which of the following is the rejection region for a right-tailed test?

• -1.28

• 1.28

• 1.645

• 1.96

What is the rejection region for a left-tailed test with unknown population variance, 𝑛=18, and with 0.01 significance level?

• −2.567

• −2.552

• 2.552

• 2.567

What is the rejection region for a right-tailed test with unknown population variance, 𝑛=20, and with 0.05 significance level?

• −1.729

• 1.729    

• 1.761

• 1.762

If the computed value is greater than the critical value in a right-tailed test, then we______________.

• retain the null hypothesis

• reject the null hypothesis

• support the null hypothesis

• fail to reject the null hypothesis

Refer to the given problem below.

 

A drink vending machine is adjusted so that, on average, it dispenses 200 ml of fruit juice with a standard deviation of 13 ml into a plastic cup. However, the machine tends to go out of adjustment and periodic checks are made to determine the average amount of fruit juice being dispensed. The operator thinks that the amount dispensed is less than 200 ml. So, to verify, a sample of 25 drinks is taken to test the adjustment of the machine and a mean of 195 is obtained.

What are the hypotheses?

• Ho: μ=195 ; Ha: μ<200

• Ho: μ=200 ; Ha: μ<200

• A. Ho: μ=195 ; Ha: μ≠200

• A. Ho: μ=200 ; Ha: μ≠200

Refer to the given problem below.

 

A drink vending machine is adjusted so that, on average, it dispenses 200 ml of fruit juice with a standard deviation of 13 ml into a plastic cup. However, the machine tends to go out of adjustment and periodic checks are made to determine the average amount of fruit juice being dispensed. The operator thinks that the amount dispensed is less than 200 ml. So, to verify, a sample of 25 drinks is taken to test the adjustment of the machine and a mean of 195 is obtained.

What test statistic should be used?

• t-test

• z-test

• z – test with sample standard deviation

• standard deviation

Refer to the given problem below.

 

A drink vending machine is adjusted so that, on average, it dispenses 200 ml of fruit juice with a standard deviation of 13 ml into a plastic cup. However, the machine tends to go out of adjustment and periodic checks are made to determine the average amount of fruit juice being dispensed. The operator thinks that the amount dispensed is less than 200 ml. So, to verify, a sample of 25 drinks is taken to test the adjustment of the machine and a mean of 195 is obtained.

What is the computed test-statistic value?

• – 2.790

• -1.923

• 2.790

• 1.923