Question

a plane left 40 min. late due to bad weather and in order to reach it's detinaton 1600km away in time, it had to increase it's speed by 400 km per hr. .from it usual speed. find the usual speed of the plane​

Answer 1

• let usual speed be x
• distance=1600 km
• usual time=1600/x
• since it is late so new time for travel is 1600/x-40/60

=(4800 -2x)/x

• new speed =(x+400)km/h

this implies 1600=(x+400) (4800-2x)/x

2400x=1920000

• x=800 km/h