Question 1154830: a plane travels at 100km/h one way and returns at 165km/h the whole trip takes 30mins. how long does it take to on the 1st trip ( 100km/h ) Found 3 solutions by Alan3354, ikleyn, greenestamps:Answer by Alan3354(69443) (Show Source):
You can put this solution on YOUR website! a plane travels at 100km/h one way and returns at 165km/h the whole trip takes 30mins. how long does it take to on the 1st trip (100km/h)
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The avg speed for the round-trip is 2*100*165/(100+165) = 6600/41 km/hr
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---> the 1 way distance = (1/2)*6600/41 km = 3300/41 km
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For the outbound part: t = d/r
t = (3300/41)/100
t = 33/41 hours
The ratio of the speeds is 100/165.
Hence, the entire time of 30 minutes consists of two time intervals with the reciprocal ratio.
So, the time for the 100 km trip is = 18.68 minutes (approximately). ANSWER
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Alan,
notice that your answer 33/41 hours = = 48.3 minutes is LONGER than 30 minutes (!)
