if the speed of an aeroplane is decreased by 120 kilometre per hour it takes 18 minutes more to travel some distance if the speed is increase by 180 kilometre per hour it takes 18 minutes less to travel the same distance find the average speed of the aeroplane and the distance
Answers
Answer:
Step-by-step explanation:
Let its average speed = x km/hr and distance = y km.
We have two conditions here.
Condition 1 :
If the speed of an aeroplane is decreased by 120 km/h, it takes 18 minutes more to travel some distance.
=> (y/x - 120) - y/x = 18/60
=> y * [1/(x - 120) - 1/x] = 18/60
Condition 2 :
If the speed is increased by 180 km/h, it takes 18 minutes less to travel the same distance.
=> (y/x) - (y/x + 180) ] = 18/60
=> y * [1/x - 1/x + 180] = 18/60
Solve 1 and 2 conditions, we will get
=> (1/x - 120) - 1/x = 1/x - 1/x + 180
=> 120(x + 180) = 180(x - 120)
=> x = 720 km/hr
Place x in condition (1).
=> y * (1/(720 - 120) - 1/720] = 18/60
=> y[1/600 - 1/720] = 18/60
=> y = 1080 km
Hence,
Average Speed = 720 km/hr and Distance = 1080 km.
#Hope my answer helped you!