Originally Posted by

**Chokfull** That's an interesting take on the problem, I hadn't thought of it like that before. My book should have clarified, I guess.

However, your answer states that $\displaystyle \mu=.203$. The book gives me .078, so either you made a mistake in your calculations, I was right about the car going up, rather than down, the slope, or the book is wrong. But it may just be the angle. The formula for the angle came from an example earlier in the book for which there was no friction, and this is why I was saying that maybe it is supposed to be assumed that there is no friction on the rainy day, seeing as this was the only formula I was given for the angle.