SOLUTION: A person covers half his journey by bus at 60 km/hr, half the remaining half by train at 30 km/hr and the rest by cycle at 10 km/hr. Find the average speed ?

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Question 699088: A person covers half his journey by bus at 60 km/hr, half the remaining half by train at 30 km/hr and the rest by cycle at 10 km/hr. Find the average speed ?
Answer by ankor@dixie-net.com(22740) (Show Source):
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A person covers half his journey by bus at 60 km/hr, half the remaining half by train at 30 km/hr and the rest by cycle at 10 km/hr. Find the average speed ?
:
Let j = total length of the journey
then
.5j = bus length
.25j = train length
.25j = bike length
:
let s = average speed of the whole journey
:
Write a time equation; time = dist/speed
:
bus time + train time + bike time = total time
+ + =
multiply by 60s to get rid of the denominators, results
.5js + 2(.25js) + 6(.25js) = 60j
.5js + .5js + 1.5js = 60j
2.5js = 60j
divide both sides by j
2.5s = 60
s = 60/2.5
s = 24 km/h, average speed for the trip