SOLUTION: Two planes took off from St. Louis, MO. The first plane is traveling 3.5 times as fast as the second plane. After traveling in the same direction for 5.5 hours, they are 1265 miles

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Question 684111: Two planes took off from St. Louis, MO. The first plane is traveling 3.5 times as fast as the second plane. After traveling in the same direction for 5.5 hours, they are 1265 miles apart. What is the average speed of each plane? ( Hint: since they are traveling in the same direction the distance between them will be the difference of their distance.)
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
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Two planes took off from St. Louis, MO.
The first plane is traveling 3.5 times as fast as the second plane.
After traveling in the same direction for 5.5 hours, they are 1265 miles apart.
What is the average speed of each plane?
:
Let s = average speed of the 2nd plane
then
3.5s = average speed of the 1st
:
Write a distance equation; dist = speed * time
:
1st plane's dist - 2nd plane dist = 1265 mi
3.5s(5.5) - 5.5s = 1265
19.25s - 5.5s = 1265
13.75s = 1265
s = 1265/13.75
s = 92 mph is the speed of the 2nd plane
then
3.5(92) = 322 mph is the speed of the 1st
:
:
Check this by finding the dist each plane traveled
5.5(322) = 1771 mi
5.5(92) = 506 mi
---------------------
difference: 1265 mi