SOLUTION: A person takes a trip, driving with a constant speed 87.3 km/h except for a 27.4 min rest stop. If the person’s average speed is 74.6 km/h, how much time is spent on the trip?

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Question 490521: A person takes a trip, driving with a constant
speed 87.3 km/h except for a 27.4 min rest
stop.
If the person’s average speed is 74.6 km/h,
how much time is spent on the trip?
Answer in units of h
How far does the person travel?
Answer in units of km
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
A person takes a trip, driving with a constant speed 87.3 km/h except for a 27.4 min rest stop.
If the person’s average speed is 74.6 km/h,how much time is spent on the trip?
Answer in units of hr
How far does the person travel?
Answer in units of km
:
Since they want the solution in units of hrs and km, we should be able to round off these annoying decimals
87.3 = 87 km
74.6 = 75 km
27.4 = 27 min, which is: 27/60 = .45 hrs
:
let d = the distance traveled
:
A simple time equation; Time = dist/speed
time at 87km/h + rest time = total time
d%2F87 + .45 = d%2F75
multiply equation by 87*75 = 6525, results
75d + 6525(.45) = 87d
75d + 2936 = 87s
2936 = 87d - 75d
2936 = 12d
d = 2936%2F12
d = 245 km
find the time spent on the trip
245%2F87 + .45 =
2.8 + .45 = 3.25 hrs
Check using the av speed
245%2F75 = 3.27 hrs, close enough