Hope someone can help with this.
Department 'A' answered 1,502 phone calls at an average answer speed of 0.01 seconds.
Department 'B' answered 890 phone calls at an average answer speed of 8.20 seconds.
The total calls answered was 2392. Department 'A' answered 62.8% of the calls and Department 'B' answered 37.2%.
What is the combined average answer speed of both Departments 'A' and 'B?'
I know that if Departments 'A' and 'B' each answered an equal number of calls, the formula would be:
8.20 + 0.01
----------- = 4.11 seconds
but it's not a 50/50 ratio. What formula would I use to account for the 63/37 split?