The centripital force is pushing the car off the road, and when the cars are moving at 60 km/h it keeps them from going off the road on the outside of the curve, where, if you notice, the guardrail is usually positioned. the banking of the road helps keep the cars on the road, rather than tipping them off. Therefore, the frictional force keeping them on the road must be towards the center. Also, I meant that the fourth force would be the turning of the car itself, wouldn't it? otherwise the car's going to head straight, and go off the road.

Also, is my equation for \(\displaystyle \theta\) right? My calculator gives \(\displaystyle \tan^{-1} \frac{(40*1000/3600)^2}{9.8*200} = .062905\), which is in radians I assume, so I multiply by 57.296 and get \(\displaystyle 3.604^o\), which seems way too small. I multiplied the 40 by 1000 and divided by 3600 to convert to m/s, rather than km/h. I'm worried that I was incorrect in working under the assumption that on the rainy day there is no friction, but if this is incorrect this problem looks impossible.