SOLUTION: 1/4 journey at 25 km/h 1/3 at 30km/h and rest at 50km/h.find average speed
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Question 997465: 1/4 journey at 25 km/h 1/3 at 30km/h and rest at 50km/h.find average speed
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
1/4 journey at 25 km/h 1/3 at 30km/h and rest at 50km/h.
find average speed
:
Let a = the average speed
We can make this easy, choose a convenient value for the distance of the trip
Dist = 120 km
them
*120 = 30 km
*120 = 40 km
and
50 km = the remainder of the trip
:
Write a time equation; time = dist/speed
+ + =
Multiply equation by 150a, cancel the denominators and you have
6a(30) + 5a(40) + 3a(50) = 150(120)
180a + 200a + 150a = 18000
530a = 18000
a = 18000/530
a = 33.96 ~ 34 km/hr is the average speed
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