This book contains plenty of problems on all the subjects covered by the AP Exam, and detailed solutions for each problem. It was very helpful in my Physics C crash course before the AP last year. The book is also good because the practice questions are harder than actual AP questions, so that the Exam seemed easy in comparison.However, the errors (either benign typos, or equations which were just wrong) were frequent enough to be somewhat annoying. I ran into an error every few pages or so.