1 A company has set a goal of developing a battery that last

1. A company has set a goal of developing a battery that lasts for more than 300 minutes in continuous use. In a first test of these batteries, the following lifespans (in minutes) resulted: 321 295 332 351 281 336 311 253 270 326 311 288

a. Find each of the values in the chart below. Round your final answers to four decimal places. sample mean sample standard deviation standard error (SE)

b. Some graphs of the data are also provided. Explain why you need to see these graphs before proceeding with a confidence interval or hypothesis test.

c. Construct a 95% confidence interval for the mean life span for this brand of battery. You may use your calculator.

d. Use your calculator or a t-table to give the critical value (t*) that would have been used in constructing the 95% confidence interval from part c.

e. Find the margin of error associated with the 95% confidence interval from part b. Show how you found it.

f. Do you have conclusive evidence that the company met its goal of a battery that lasts longer than 300 minutes? Explain why or why not based on the confidence interval results.

Solution