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avatar+819 

I drove to the beach at a rate of 40 miles per hour.  If I had driven at a rate of 50 miles per hour instead, then I would have arrived 25 minutes earlier.  How many miles did I drive?

 Aug 4, 2023
 #1
avatar+128794 
+1

Call the time in minutes driving 40 mph =  M

 

Using Distance / Rate = Time......  we have in  the first case

 

D / 40 = M     (1)

 

In the second case we must convert 25 min  to hrs = 25/60hrs =  5/12 hrs....so we have that

 

D / 50 = M - 5/12   (2)

 

Sub (1) into (2)

 

D /50  = D/40 - 5/12   rearrange as

 

D/40 - D/50 =  5/12

 

5D / 200 - 4D /200  =  5/12

 

D / 200  = 5/12

 

D = 200 * 5/12  =  1000/12 = 250 / 3  miles =  83 1/3 miles 

 

cool cool cool

 Aug 4, 2023

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