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Kerri drives  150 miles to visit her grandmother. She starts off driving at 60  miles per hour, but then encounters road construction and has to drive 20 miles per hour the rest of the way. If she spends the same amount of time at the faster speed as at the slower speed, then how many hours did her 150-mile trip take in total?

 Jan 25, 2019
 #1
avatar+16398 
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60 m/h * x hr    + 20 m/h * x hr   = 150 m

80x = 150

x=1.875  hr       at each speed   =  3.75 hours total  = 3 hr 45 min total travel time    

 

  

1.875(60)  + 1.875 (20) = 150

 Jan 25, 2019
edited by ElectricPavlov  Jan 25, 2019
 #2
avatar+96208 
+1

Let the time at both speeds = T

 

So

 

Distance at 60 mph + Distance at 20 mph  = 150

 

60T + 20T =  150

 

80T = 150

 

T =  150 / 80  =   15/8   hrs at both speeds

 

 

So.....the total time =  15/8 + 15/8 =   30 /8 hrs   = 3.75 hrs

 

 

 

cool cool cool

 Jan 25, 2019

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