Probabilities of picking aces from a deck of cards

[LemMoN]

So I have a deck with 36 cards containing 4 aces. After extracting 3 random cards:
a) What is the probability of being EXACTLY 1 ace in those 3 cards?
b) What is the probability of being AT LEAST an ace in those 3 cards?

 

[Prof]

Please read the guidelines for the site. You should submit some work, and then we will help you continue from there. See what you can write for part a, such as the probability of picking an ace as one card, and then how to deal with the fact that there are 3 cards. You should have some formulas in your math book.

 

[HallsofIvy]

There are 36 cards, 4 of which are aces. What is the probability the first card drawn is an ace? If the first card is an ace, there are 35 cards left 3 of which are aces. What is the probability the next card drawn is NOT an ace? If the second card drawn is NOT an ace there are 34 cards left, 3 of which are aces. What is the probability the third card is NOT an ace? If the third card is NOT an ace, there are 33 cards left, 3 of which are aces. What is the probability the fourth card is NOT an ace? So what is the probability the first card drawn is an ace and the other three are not? What about the 3 other possible orders of "one ace,l three not aces"?

The probability of "at least one ace" is 1 minus the probability of "all non-aces" which can be calculated in the same way.