In a aeroplane, the fuel burnt is directly proportional to the square root of its speed. If the aeroplane travels 800 km at a speed of 441 km/hr, the amount of fuel burnt is equal to 1250 litres. Find the distance travelled by the aeroplane, if 2000 litres of fuel was burnt while travelling at 784 km/hr.

Hi,

Lets assume that for every hour the fuel burnt is given by k(squareroot (speed))

So, in the first case 1,

1250/800 = k squareroot (441) => k = 1250/(800 X 21)

Let's suppose in the second case it travelled x distance. So,

2000/x =  1250/(800 X 21) squareroot (784) 

=> 2000/x =  1250/(800 X 21) X 28

Solving for x we will get the answer.