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Bob can drive 50 miles in 40 minutes. Sam can drive 90 miles in 105 minutes. If d is the time (in hours) it takes for Bob to drive 120 miles and e (in hours) is the time it takes for Sam to drive 120 miles, what is the |d-e|? Express your answer as a decimal to the nearest hundredth.

 Feb 17, 2020
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Bob can drive 50 miles in 40 minutes. Sam can drive 90 miles in 105 minutes. If d is the time (in hours) it takes for Bob to drive 120 miles and e (in hours) is the time it takes for Sam to drive 120 miles, what is the |d-e|? Express your answer as a decimal to the nearest hundredth.

 

Bob  drives    50 mi /40 min  = (5/4)mi /min

 

So the time it takes him to  drive  120 mi    =     120  / [5/4] = 120 * 4  / 5=   96 min =  96/60 =  8/5 hrs

 

 

Sam drives    90 /105 =  6/7  mi/ min

 

So....the time it takes him to  drive   120 miles =  120 / [6/7 ]  =   120 * 7 / 6 =  140 min  =  7/3 hrs  

 

So  l  d  - e  l    =   l 8/5 - 7/3  l   =  l (24 - 35) / 15  l  =   l  -11 / 15  l  =   11/ 15  ≈  0.73

 

 

cool cool cool

 Feb 17, 2020

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