SOLUTION: At 1:30 a plane leaves tuscon for baltimore, a distance of 2240 miles. The plane flies at 280mph. A second plane leaves at 2:15 and is schedules to land in baltimore 15 minutes b

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Question 167934: At 1:30 a plane leaves tuscon for baltimore, a distance of 2240 miles. The plane flies at 280mph. A second plane leaves at 2:15 and is schedules to land in baltimore 15 minutes before the first plane. At what rate must the second air plane travel to arrive on schedule.
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
The distance, 2240, is the same for both planes
For 1st plane:
(1) d+=+r%5B1%5D%2At%5B1%5D
For 2nd plane:
(2) d+=+r%5B2%5D%2At%5B2%5D
(3) r%5B1%5D%2At%5B1%5D+=+r%5B2%5D%2At%5B2%5D
It is given that r%5B1%5D+=+280 mi/hr
From (1)
(1) d+=+r%5B1%5D%2At%5B1%5D
2240+=+280%2At%5B1%5D
t%5B1%5D+=+8
The 2nd plane leaves 45 min later and arrives 15 min earlier,
so it spends 1 hr less in the air than the 1st plane
t%5B2%5D+=+t%5B1%5D+-+1
From (3)
280%2At%5B1%5D+=+r%5B2%5D%2A%28t%5B1%5D+-+1%29
r%5B2%5D+=+280t%5B1%5D+%2F+%28t%5B1%5D+-+1%29
r%5B2%5D+=+280%2A8+%2F+%288+-+1%29
r%5B2%5D+=+2240+%2F+7
r%5B2%5D+=+320 mi/hr
check answer:
(3) r%5B1%5D%2At%5B1%5D+=+r%5B2%5D%2At%5B2%5D
280%2A8+=+320%2A7
2240+=+2240
OK