A curve with a 120 m radius on a level road is banked at the correct angle for a speed of 20 {\rm m/s}.

A curve with a 120 m radius on a level road is banked at the correct angle for a speed of 20 {rm m/s}.If an automobile rounds this curve at 30 {rm m/s}, what is the minimum coefficient of static friction between tires and road needed to prevent skidding?