SOLUTION: Two planes leave O'Hare Airport Chicago at the came time. One flies directly east at 540 miles per hour. the other flies directly west at 720 miles per hour. How long will it take

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Question 150076: Two planes leave O'Hare Airport Chicago at the came time. One flies directly east at 540 miles per hour. the other flies directly west at 720 miles per hour. How long will it take them to be 1890 miles apart?
Found 2 solutions by nerdybill, ankor@dixie-net.com:
Answer by nerdybill(7384) (Show Source):
You can put this solution on YOUR website!
Two planes leave O'Hare Airport Chicago at the came time. One flies directly east at 540 miles per hour. the other flies directly west at 720 miles per hour. How long will it take them to be 1890 miles apart?
.
Here, you are expected to know the relationship:
D = RT
where
D is distance
R is "rate" or speed
T is time
.
Let T = time flown in hours
then
"distance traveled by eastbound plane" = 540T
"distance traveled by westbound plane" = 720T
.
"distance traveled by eastbound plane" + "distance traveled by westbound plane" = "distance apart"
OR, we have:
540T + 720T = 1890
1260T = 1890
T = 1890/1260
T = 1.5 hours

Answer by ankor@dixie-net.com(22740) (Show Source):
You can put this solution on YOUR website!
Two planes leave O'Hare Airport Chicago at the came time. One flies directly east at 540 miles per hour. the other flies directly west at 720 miles per hour. How long will it take them to be 1890 miles apart?
:
Let t = time (in hrs) that the planes are 1890 mi apart
:
Write a distance equation: dist = speed * time
:
540t + 720t = 1890
:
1260t = 1890
t =
t = 1.5 hrs
:
:
Check solution
1.5 * 540 = 810
1.5 * 720 = 1080
-----------------
total dist= 1890