henilshaht wrote:
A plane can travel 200 miles on 50 gallons of jet fuel when it flies at 10,000 feet.It can travel 300 miles on 50 gallons of jet fuel when it flies at 20,000 feet. Which of the following is closest to the number of miles per gallon that the plane will average if it flies for 1,000 miles at 10,000 feet and 3,000 miles at 20,000 feet?
A. 3
B. 4
C. 5
D. 6
E. 7
I am slightly confused here. This is the approach I followed. But I got the answer wrong. Can someone help me here:
-> at 10000 feet, mileage is 4 miles/ gallon
-> at 20000 feet, mileage is 6 miles/ gallon
->now it is covering 1000 miles at 10000 feet and 3000 miles at 20000 feet
-> that means that 1/4 = 0.25 distance is covered at 10000 feet and 0.75 distance is covered at 20000 feet
so shouldn't it be :
0.25 * 4 + 0.75*6
=5.5
They are getting 5.33
Given: A plane can travel 200 miles on 50 gallons of jet fuel when it flies at 10,000 feet.It can travel 300 miles on 50 gallons of jet fuel when it flies at 20,000 feet.
Asked: Which of the following is closest to the number of miles per gallon that the plane will average if it flies for 1,000 miles at 10,000 feet and 3,000 miles at 20,000 feet?
At 1000 feet:
miles / gallon = 200/50 = 4 miles/gallon
miles travelled = 1000 miles
Fuel used = 250 gallons
At 20,000 feet:
miles/gallon = 300/50 = 6 miles/gallon
miles travelled = 3000 miles
Fuel used = 500 gallons
Average miles / gallon = Total miles travelled / Total fuel consumed = 4000/750 = 5 1/3 = 5.33 miles/gallon
which is closest to 5 miles/gallon
IMO C
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