Question 253110: Can you please help me solve this word problem, I have tried multiple times and cannot figure it out, thank you for your help :
Two planes start from the same airport and fly in opposite directions. The second plane starts 1/2 hour after the first plane, but its speed is 80 km per hour faster. Find the groundspeed of each plane if 2 hours after the first plane departs the planes are 3200 km apart.
Answer by Edwin McCravy(20056)   (Show Source):
You can put this solution on YOUR website! Two planes start from the same airport and fly in opposite directions. The second plane starts 1/2 hour after the first plane, but its speed is 80 km per hour faster. Find the groundspeed of each plane if 2 hours after the first plane departs the planes are 3200 km apart.
Make this chart
DISTANCE RATE TIME
first plane
second plane
Let the rate of the first plane be x
Let the rate of the second plane be 80 kph more or x+80
Fill those in:
DISTANCE RATE TIME
first plane x
second plane x+80
The first plane's time was 2 hours
The second plane's time was a half hour less or 2-.5 or 1.5 hours
DISTANCE RATE TIME
first plane x 2
second plane x+80 1.5
Use D=RT to fill in the distances
DISTANCE RATE TIME
first plane 2x x 2
second plane 1.5(x+80) x+80 1.5
They are 3200 km apart, so the sum of their distances
equals 3200
2x + 1.5(x+80) = 3200
Can you solve that? If both post again asking how:
Answer: x=880
The first plane was traveling 880 kph and the second
plane was traveling 80kph faster or 960 kph.
Edwin
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