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# Speed Question

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A train is scheduled to make a 616 mile trip in 9 hours. The train averages 60 mph during the first 240 miles and 80 mph during the next 160 miles. What must be the average speed of the train for the remainder of the trip in order for the train to arrive on schedule?

Oct 18, 2017

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A train is scheduled to make a 616 mile trip in 9 hours. The train averages 60 mph during the first 240 miles and 80 mph during the next 160 miles. What must be the average speed of the train for the remainder of the trip in order for the train to arrive on schedule?

Time traveled in the first part  =  240 / 60  =  4 hrs

Time traveled  in the second part = 180 / 80  =  2 hrs

So......240 + 160  =  400 miles have been traveled

And  616 - 400  =  216  miles are left to travel

And  there are 3 hours left to travel

So

Distance left to travel / Time left to travel  = Rate  =  216 / 3  = 72 mph

So.....the train must average 72 mph to finsih the trip on time

Oct 18, 2017