Question

Flying against the wind, an airplane travels 3750 kilometers in 5 hours. Flying with the wind, the same plane travels 7910 kilometers in 7 hours. What is the rate of the plane in still air and what is the rate of the wind?

Answer 1

against the wind, an airplane travels 3750 km in 5 hours

with the wind the same plane travels 7910 km in 7 hours

let speed of plane in still air be x km/h

speed of wind be y km/h.

t=d/r

5 = (3750)/(x - y)

3750 = 5x - 5y

750 = x - y (1)

7910/(x + y) = 7

7910 = 7(x + y)

1130 = x + y (2)

Add (1) & (2)

2x = 1880

x = 940 km/h speed of plane in still air

Now plug value of x in (2)

1130 = 940 + y

y = 1130 - 940 = 190 km/h speed of wind