SOLUTION: If I need to drive 120 km in 120 minutes and for the first half an hour travel at 70km/h how fast will I have to travel to make it on time

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Question 956621: If I need to drive 120 km in 120 minutes and for the first half an hour travel at 70km/h how fast will I have to travel to make it on time
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
If I need to drive 120 km in 120 minutes, and for the first half an hour travel at 70km/h, how fast will I have to travel to make it on time?
:
Let s = the speed required on the remaining part of the trip in 90 min (1.5 hrs)
Find the distance traveled in 1/2 hr at 70 mph
1%2F2 * 70 = 35 mi
Find the distance traveled at some other speed
120 - 35 = 85 km
Find the speed you have to drive to travel 85 km in 1.5 hrs
85%2Fs = 1.5
1.5s = 85
s = 85/1.5
s = 562%2F3 km/hr