What are the chances of being pregnant if the guy wore a condom and pulled out before he ejaculated?

First, the condom (if it's not defective) would have blocked all the sperm from entering you even if he hadn't pulled out.

Condoms are only 97% effective, meaning there is a very small chance that sperm can get through anyways, but adding pulling out prior to ejaculating ups your chances of avoiding conception.

But pulling out isn't any fun, it ruins the guy's orgasm. If you're concerned about safe methods of Birth Control, try condoms with spermacide on them. It will kill the sperm. Or go on the birth control pill as well as using a condom. A backup plan is always a good idea since no method of birth control is 100% effective. The pill, if taken correctly, is about 98% effective. Personally, using condoms and taking the pill correctly is my surefire way of preventing pregnancy.