Question

If the speed of an aeroplane is decreased by 120km/h it take 18minutes more to travel some distance if the speed increased by 180km/h it take 18 minutes less to travel the same distance. Find the average speed of aeroplane and the distance

Answer 1

Answer: av spedd = 720km/h & total distance = 1080km

Step-by-step explanation:

Let, the average speed of the aeroplane be denoted by “x” km/hr and the distance travelled by it be denoted by “y” km.

According to question, equation follows like this:

for, Speed decrease:

Y/X-120 - Y/X = 18/60.........equation I

for, Speed Increase:

Y/X - Y/X+180 = 18/60.........equation II

From equation I & II we get

120 (x+180) = 180 (x-120)

2x + 360 = 3x - 360  

x = 720 km/hr (av. speed)

Substituting the value of x = 720 km/hr in equation I, we get

Y/720-120 - Y/720 = 18/60

Y = 1080km