Calculating Force problem

[pennywise1234]

Homework Statement

A high jumper with a body weight of 800N exerts a force of 3 kN against the ground during takeoff.
How much force is exerted by the ground on the high jumper?

Homework Equations

f=m x a
a=f/m

The Attempt at a Solution

I converted 800n into KN giving me 0.8

I then divided a=3kn/0.8kn

is this right?

if not, how do i fix the issue

 

[Doc Al]

Hint: It's a trick question! (Consider Newton's 3rd law.)

 

[pennywise1234]

so 3kn, because every action has equal and opposite reaction. thank you