55.5mph
Explanation
First lets find the total time driven.
15+180+45= 240
Now knowing they drove for 240 minutes we can use percentages to see the percent driven at a certain speed in this time.
There are many ways to do this but heres how I did it.
I then multipled the speed by the number of minutes to find the average.
48×15= 720
60×180= 10800
40×45= 1800
These represent total miles driven in that time but we dont need that, to find the average we then need to add them all together.
720+10800+1800= 13320
Now we can divide this number by 240 to find the real average, because 240 is the whole time driven.
Our answer is 55.5
So we now know the average speed driven is 55.5
