Expert: Sherry Wallin - 8/22/2010

Question
Here is a few questions I cant answer and very confused on

1. Two numbers are randomly selected without replacement from the set {1,2,3,4,5}. Find the  probability that both numbers are even?

2. A three member committee is selected randomly from a group of 5 men and 3 women. Find the probability that all committee members are men? What is the probability that all committee members are women?

3. A die is rolled, What is the probability that the number rolled is not a "3"?

4. Consider 2 events A and B. If P (A) = 0.41 and P(B) = 0.13, what is the probability that either A or B will occur if A,B are mutually exclusive?

5. A card is drawn at random from a standard deck of cards. What is the probability that the card is either a Queen or a Diamond?

6. A die is rolled. What are the odds in favor of rolling a "6"?

7. If the odds in favor of a Laker victory in the NBA basketball payoffs is 2 to 1, what is the probability  that the Lakers will win?  

Answer
Jennifer~

Always start with one or two questions and show what work you have tried if you want an expert to really help you. I will show you how to work a couple of the problems:

#1:  Without replacement basically means you are using the same set twice with no changes in it. So how many elements are in the set? Well 5. and how many of those are even? Well there are two even numbers. So the probability on one draw of an even number being chosen is 2/5. Since the set is reused it is just the same probability on the 2nd draw, that is 2/5 but the multiplication rule says that the total probability is (2/5)*(2/5) = 4/25 of getting both numbers even (which is 16% if the time)

#3: not a 3 means the number can be any number but 3. How many numbers are there on a die? There are 6 and 5 of them are not a 3 so 5/6 of the time you will get a number that is not a 3.

#5: How many diamonds and queens are in a deck of cards? well there are 13 diamonds and 4 queens but one of those queens is a diamond so there are 13 + 3 cards that are either a diamond or a queen out of 52 cards. So the probability that the card is either a diamond or a queen is 16/52 = 4/13

Math Prof