Use the pivot table function to group all the like times and average the value. The wizard should make it easy to do. Pivot tables are very handy things to learn how to use. The option is under Data on the menus.
It is a longwinded way of doing it but would only take a few minutes and once you start using formulas you get better at finding ways to manipulate Excel data. You can recycle solutions for one problem many times.
While I am sure the other ways work, there may be an easier solution.
(I am using the Swedish language version of Excel so my translations of menu-names could be a bit off).
Go in under Data in the menu (the heading where you have functions like Sorting and Filters). Then choose the “Sums” command (It is called Delsummor in my version, don’t know the English word though). It will allow you to mark an area and you can get sums, averages, max, mins etc of any number of columns. You also choose when to sum so one can do such things as calculate the sums of sales at every change in the month column.