Question 1026491: Smith was traveling X miles to Boston at M miles per hour and arrived 2 hours late for the party. How fast should he have traveled to have arrived on time? ---
I got xm/x/m-2, which I know is wrong. An explanation of how to do this problem correctly would be greatly appreciated. Thanks!
Answer by Boreal(15235)   (Show Source):
You can put this solution on YOUR website! The distance is x miles
the speed is M mph
the time it took is miles/miles per hour, and that is x/M
The speed he needed was two hours less than that, or (x/M)-2, or (x-2M)/M. Those units are mph
The distance is unchanged, and its units are miles.
The speed needed is xM/(x-2M).ANSWER
Try an example.
480 miles, and he drove at 60 mph, taking 8 hours. He needed to get there in 6 hours, so he needed to drive 80 mph.
Use the speed he went, 60 mph
480*60/(480-120)=480*60/360
This is (1/6)*480=80 mph
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