What Speeds Are Safe for a Banked Curve in Wet Conditions?

[a.wright]

Homework Statement

the curve has a radius of 300m and is banked at an angle of 10.0degrees. (a) what speed is no friction required? (b)suppose it is raining and the coefficient of friction is 0.4, what are the maximum and minimum speeds at which the curve can be travelled

Homework Equations

Fc=mv²/r
Fnet=0

The Attempt at a Solution

i attached my work. i think i have the right answer to part (a) and think I'm on the right track for part (b) but i don't know how to get two speeds, i only end up wit one.
any help would be great. thanks

 

[RoyalCat]

Consider what the friction can keep the car from doing, it can either be used to keep the car from sliding down the ramp, but it could also be the reason it doesn't slip up the ramp.