SOLUTION: A family wanted to get to another town by 5:00 PM. They had to travel 140 miles. The speed limit was 70 miles an hour. At what time should they leave home? Assume that they would b

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Question 254179: A family wanted to get to another town by 5:00 PM. They had to travel 140 miles. The speed limit was 70 miles an hour. At what time should they leave home? Assume that they would be driving at the speed limit and there would be no traffic jams.
Found 3 solutions by rfer, richwmiller, solver91311:
Answer by rfer(16322) About Me  (Show Source):
Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!
rt=d
rate *time =distance
70*t=140
solve for t
subtract t from 5:00pm
Actually you have to get from the house to the highway which can take a bit of time but math problems generally don't take in all the details such as how long it takes to get up to 70mph and how long it takes to decelerate from 70 to zero and get in and out of the car.

Answer by solver91311(24713) About Me  (Show Source):
You can put this solution on YOUR website!


Distance equals rate times time which is to say that time equals distance divided by rate. Divide the distance they have to travel (140 miles) by the rate they will be travelling (70 miles per hour) to get the number of hours they will be travelling. Then count back from 5:00 PM that many hours and you have the time they need to leave.

By the way, it is probably ok to assume no traffic jams and travelling the speed limit, but you had better add an extra 10 minutes because you can't assume that Susie won't have to "go potty" somewhere along the way.

John