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Bob was driving home at an average speed of 40mph for 2 hours. How fast should he drive for the next 1 hour to have an average speed of 50mph?

 Mar 31, 2020
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Distance   / Time  = Rate

 

Let  R  be  the  rate  we  are  looking for  ...so.....

 

 

[ 40(2)  + R(1)  ]

_______________  =   50          simplify

         3

 

80  +  R  =  50 * 3

 

80 + R   =   150      subtract  80 from both sides

 

R = 70    (mph)

 

 

cool cool cool

 Mar 31, 2020

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