Problema Solution
An Air Force plane left London and flew
north at an average speed of 200 km/h.
Some time later a cargo plane left flying in
the same direction but at an average speed
of 220 km/h. After flying for ten hours the
cargo plane caught up with the Air Force
plane. Find the number of hours the Air
Force plane flew before the cargo plane
caught up.
Answer provided by our tutors
let
t1 = the number of hours the Air Force plane flew before the cargo plane caught up
v1 = 200 km/h the avg. speed of the Air Force plane
v2 = 220 km/h the avg.plane of the cargo plane
t2 = 10 hr the time of the flying of the cargo plane
since avg.speed = distance/time we have distance = avg.speed*time
both planes flew the same distance thus
v1*t1 = v2*t2
200*t1 = 220*10
by solving we find
t1 = 11 hr
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The Air Force plane flew 11 hours before the cargo plane caught up.