SOLUTION: A man is driving to his vacation home which is 125 miles away. The trip usually takes him 2 hours when he drives straight through. He drives at his normal speed until 40 miles into

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Question 1155417: A man is driving to his vacation home which is 125 miles away. The trip usually takes him 2 hours when he drives straight through. He drives at his normal speed until 40 miles into his trip when he decides to stop for 10 minutes to get some McDonald’s drive through. At what speed must he drive for the remainder of the trip to complete the trip in the usual amount of time?
Answer by ikleyn(52754) About Me  (Show Source):
You can put this solution on YOUR website!
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From the condition, his normal speed is  125%2F2 = 62.5 mph.


The time equation for the rest of the trip  of 125 - 40 = 85 miles long is


    85%2F62.5 - 85%2Fx = 1%2F6  of an hour (which is 10 minutes).


In this equation, x is the speed under the problem's question.


So,  85%2Fx = 85%2F62.5 - 1%2F6 = 1.19333,


and then the required speed is  x = 85%2F1.19333 = 71.23 mph.    ANSWER

Solved.