Answer: The coefficient of friction is 0.35
Explanation:
We can write the friction force as:
F = N*μ
Where N is the normal force between the refrigerator and the ground, as the full weight of the refrigerator is acting on the ground, the normal force will be exactly equal to the weight of the refrigerator, then:
N = 650N
And μ is the coefficient of friction.
And for this case, the force is 230N, then we have:
F = N*μ
230N = 650N*μ
(230N/650N) = μ = 0.35
Notice that the distance did not matter for this calculation.