$(30$ points total$)$ Consider the following study involving four battery brands $($A$,$ B$,$ C$,$ and

D$),$ operating conditions $($room temperature or cold$)$ and the time for the battery to fail

once a load is placed on it$.$ The data is in the text file BatteryFail.txt$.$ You may copy and

paste the contents of BatteryFail.txt into data lines in a SAS data step you create. There

should be three variables: one indicating the time to failure, one for the temperature

condition, and one for the brand.

a$.(15$ points$)$ Use PROC MEANS to display the mean and median of time to failure for

each of the four brands. Compare the four brands based on mean and median. Write

your answer as a comment in your SAS program.

b$.(15$ points$)$ Use PROC MEANS to display the mean and median of time to failure for

the two operating conditions. Compare the operating conditions based on mean and

median. Write your answer as a comment in your SAS program.