If a curve with a radius of 65 m is properly banked for a car traveling 75 km/h, what must be the coefficient of static friction for a car not to skid when traveling at 104 km/h?

As a car makes a turn, the force of friction acting upon the turned wheels of the car provides centripetal force required for circular motion. Equation to follow are F = mv²/r  "Force of friction"  Ff= μsN, Normal N=mg Ff=μsmg. Therfore
mv²/r = μsmg  cancel mass "m" The formula to follow will be μs = v²/rg
 
μs = v²/rg  μs = (28.89 m/s²)²/ (65 m)(9.8 m/s²) =  1.31