48, which is practical.
Work Step by Step
To be 95% confident that s is witin 20% of $\sigma$ by using the table, the corresponding sample size is: 48, which is quite small and hence practical.
You can help us out by revising, improving and updating this answer.Update this answer
After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.