Answer:
x = 302 m
Step-by-step explanation:
Given that,
Speed of an airplane, v = 40 m/s
Height, h = 280 m
40 m/s is the horizontal velocity we should use to solve the given problem.
Let t is the time when the hay will reach the ground. It can be calculated using second equation of motion as follows :

Here, u = 0 and a = g

Let the horizontal distance is x. It can be calculated as :
x = vt
x = 40 m/s × (7.55 s)
x = 302 m
Hence, at a distance of 302 m she have to release the hay in order to hit the cow.