In: Statistics and Probability
For a certain drug, based on standards set by the United States Pharmacopeia (USP) - an official public standards-setting authority for all prescription and over-the-counter medicines and other health care products manufactured or sold in the United States, a standard deviation of capsule weights of less than 0.8 mg is acceptable. A sample of 20 capsules was taken and the weights are provided below:
| 120.3 | 120.8 | 120.1 | 119.7 | 120.8 | 
| 119.4 | 119.1 | 120.9 | 118.9 | 119.5 | 
| 120.4 | 121.1 | 118.6 | 119.4 | 119.3 | 
| 119.8 | 120.2 | 119.5 | 118.9 | 119.8 | 
(Note: The average and the standard deviation of the data are respectively 119.8 g and 0.73 g.)
At 5% significance level, test the claim that the standard deviation of capsule weights of the drug is different from 0.8 g.
Procedure: Select an answer One mean Z Hypothesis Test One mean T Hypothesis Test One proportion Z Hypothesis Test One variance χ² Hypothesis Test
Assumptions: (select everything that applies)
Step 1. Hypotheses Set-Up:
| H0:H0: Select an answer p σ² μ = | , where ? p μ σ is the Select an answer population proportion population standard deviation population mean and the units are ? lbs g mg kg | 
| Ha:Ha: Select an answer μ p σ² ? > ≠ < | , and the test is Select an answer Right-Tail Left-Tail Two-Tail | 
Step 2. The significance level α=α= %
Step 3. Compute the value of the test statistic: Select an answer z₀ f₀ χ²₀ t₀ = (Round the answer to 3 decimal places)
Step 4. Testing Procedure: (Round the answers to 3 decimal places)
| CVA | PVA | 
| Provide the critical value(s) for the Rejection Region: | Compute the P-value of the test statistic: | 
| left CV is and right CV is | P-value is | 
Step 5. Decision:
| CVA | PVA | 
| Is the test statistic in the rejection region? | Is the P-value less than the significance level? | 
| ? yes no | ? yes no | 
Conclusion: Select an answer Do not reject the null hypothesis in favor of the alternative. Reject the null hypothesis in favor of the alternative.
Step 6. Interpretation:
At 5% significance level we Select an answer DO DO NOT have sufficient evidence to reject the null hypothesis in favor of the alternative hypothesis.