The average wait time is simply the averages of all the wait times in a product category. For instance, a custom watch manufacturer might have a wait time that ranges from 5 days to 10 days for a model A watch depending on the options. The average wait time for the model A watch is 7.5 days.
If your asking how many chips there are in total... it would be 15
With data, you can have outliers. Outliers are values that do not follow what the range or majority of the data you collected so a value of 45, 42, 45, 48, 42, 44, 88, the mean will obviously be different because the 88 is going to change the whole data. But, if you put it from least to greatest, you can see what the majority of data is, (what the middle value is) to see what is in the middle range of what you have collect- the outliers don't affect what you have. Hence, 42, 42, 44, 45, 45, 88 (it's not much data) but it can show what the majority of data is. Hope this helps :> :)
I don't think you can because the variables are different. You can only add the same variables.