If at all possible, please guide me through these two problems in Excel. I need assistance with the steps in the process. The database with queue times and service times is already on this site, Again, I need assistance with the steps, so the data is not absolutely necessary. The first problem is a z-test and the second problem is choice based on best fit. Please explain. Thank you!

First, test of hypothesis to determine whether the average TiQ is lower than the industry standard of 2.5 minutes (150 seconds). Consider using a z-test (Z.TEST in Excel); if you choose this test, you can either (1) estimate the standard deviation from the sample data (STDEV.S in Excel), or (2) leave the standard deviation blank and Excel will calculate it from the sample data.

Then, you are asked to perform a test of hypothesis to determine whether the average ST with service protocol PE is lower than with the PT protocol. The hint says, this should be a test of means for two independent groups. In Data Analysis in Excel, there are three two-sample tests for independent samples (groups): two t-tests, one assuming equal variances and the other assuming unequal variances, and a z-test. Whichever test you choose, be sure to explain your choice.

For both hypothesis tests, "is lower than" (<) is a one-tailed test to the left. Sometimes Excel permits you to specify the number of tails [one (1) or two (2)], and sometimes not. If not, the Excel default is a two-tailed test, so be sure to interpret the p-value [prob-value, probability value] correctly for a one-tailed test to the left.