The correct answer is B) 305 N.
The maximum force of friction between the bookcase and the floor is given by
[tex]F=\mu m g[/tex]
where
[tex]\mu=0.82 [/tex] is the coefficient of friction
[tex]m=38 kg[/tex] is the mass of the bookcase
[tex]g=9.81 m/s^2[/tex] is the gravitational acceleration.
By substituting the data of the problem into the formula, we find
[tex]F=(0.82)(38 kg)(9.81 m/s^2)=305 N[/tex]
