IMO, an intelligent, thoughtful person will score a 95% grade on the written test if they just read the questions closely, don't hurry, and apply common sense. At minimum, I can't imagine failing it.Just read up on the Texas gun laws before you take the class it makes it even easier.
Come to think of it, I can't imagine failing the shooting test, either. I've seen it failed just twice; in both cases, the shooter passed on their re-shoot.