Stats Homework

1. 459 randomly selected light bulbs were tested in a laboratory, 291 lasted more than 500 hours. Find a point estimate of the true proportion of all light bulbs that last more than 500 hours.

2. Find the critical value for zα/2 that corresponds to a degree of confidence of 98%.

3. Find the margin of error for the 95% confidence interval used to estimate the population proportion with n = 163 and x = 96.

4. Construct the confidence interval for question 3.

5. Interpret the confidence interval found in question 4.

6. Under what circumstances do we need to use a Student’s t-distribution to calculate the population mean?

7. Find the critical value for tα/2 corresponding to n = 12 and 95% confidence level.

8. Use the confidence level and sample data to find the margin of error E.

College students’ annual earnings: