When to use addition or multiplication in probability?

I am confused about "and" and "or" problems. For example:

When drawing a single card, what is the probability of getting a 4 **or** a diamond?

When drawing a single card, what is the probability of getting a jack **and** a black card?

Do the words and/or dictate whether or not I am supposed to use addition or multiplication? My teacher has not done a good job of explaining this.

Thanks in advance if you can help me. (Smile)

Re: When to use addition or multiplication in probability?