two planes leave NAIA airport at the same time. one travels North at 680 miles per hour and the other travels South at 620 mph. how long will it take for the two planes to be 3900 miles apart?

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the one who travels north at 680 miles apart will take 5.73 and the south is 6.29 mies apart...

Answers

2014-01-27T14:00:47+08:00
Given:
680 miles per hour going north
620 miles per hour going south
required: time at 3900 miles apart

we know that the plane flight at there opposite ways ..the first plane going to north and the second plane going to south but in 1 hour they took about 1300 miles apart therefore if they took 3900 miles apart they reach 3 hours.

680miles + 620miles/hour = 3900miles
1300miles/hour=3900miles
hour = 3900miles/1300miles
time = 3 hours.
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