1. Acme Corporation manufactures light bulbs. The CEO claims that an average Acme light bulb lasts 300 days. A researcher randomly selects 30 bulbs for testing. The sampled bulbs last an average of 310 days, with a standard deviation of 25 days.
a) How many degrees of freedom are there?
b) Using a t-distribution table, find the critical value t* for a 90% confidence interval.
c) Form a 90% confidence interval for the mean life of a light bulb made by Acme Corporation. (Round the answers to three decimal places.)
f) Find the test statistic (show work).
g) Find the P-value (show work).