Question 1189340: A 747 airplane is fully refueled before takeoff. The 747 uses approximately 600 gallons of fuel per minute while flying at the speed of 600 mph and approximately 500 gallons per minute while flying at the speed of 500 mph. The plane flies for 3 hours at the rate of 600 mph and then slows down for the last 2 hours to 500 mph. On this entire flight what was the average number of gallons per mile used by the airplane?
Found 2 solutions by Theo, ikleyn:
Answer by Theo(13342)   (Show Source):
You can put this solution on YOUR website! the plane uses 600 gallons per minute at 600 miles per hour and 500 gallons per minute at 500 miles per hour.
there are 60 minutes in an hour
the plane uses 600 * 60 = 36000 gallons per hour when the plane is traveling at 600 miles per hour.
the plane uses 500 * 60 = 30000 gallons per hour when the plan is traveling at 500 miles per hour.
the plane flies at 600 miles per hour for 3 hours.
the total number of miles traveled is 3 * 600 = 1800 miles.
the total number of gallons used is 3 * 36000 = 108000 gallons.
the plane flies at 500 miles per hour for 2 hours.
the total number of miles traveled is 2 * 500 = 1000 miles
the total number of gallons used is 2 * 30000 = 60000 gallons.
the plane flew a total of 2800 miles and used a total of 168000 gallons.
the average number of gallons per mile used by the plane was 168000 / 2800 = 60.
Answer by ikleyn(52781)  (Show Source):
You can put this solution on YOUR website! .
A 747 airplane is fully refueled before takeoff.
The 747 uses approximately 600 gallons of fuel per minute while flying at the speed of 600 mph
and approximately 500 gallons per minute while flying at the speed of 500 mph.
The plane flies for 3 hours at the rate of 600 mph and then slows down for the last 2 hours to 500 mph.
On this entire flight what was the average number of gallons per mile used by the airplane?
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The average number of gallons per mile =  =  = 60 gallons per mile.
Solved.
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Let's make some post-solution estimations.
60 gallons of fuel per mile means 60,000 gallons per 1,000 miles, which is
about 4*60,000 liters of fuel per 1,000 miles, or about 240 metric tons per 1,000 miles,
which is, OBVIOUSLY, absolutely unrealistic.
We all know that the airplanes are apparatuses heavier than air, but with such great load
as 240 metric tons of fuel, no one plane could be able takeoff.
It is interesting to compare this figure with what other (professional) sources tell about it.
Internet web-site https://executiveflyers.com/how-much-fuel-does-a-boeing-747-hold/
says that B-747 burns approximately 5 gallons of fuel per mile.
It also says that the B-747 is actually a very efficient aircraft and beats other modes of transportation by a long way.
So, the input data in this problem OVER-ESTIMATEs the fuel rate/consumption of B-747 in 10 ( ten, TEN ) times ( ! ) ( ! )
My warm greetings to the composer of this problem ( ! )
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