Practice with
Conditional Probability
Topic Index | Algebra Index | Regents Exam Prep Center

 

Answer the following questions dealing with conditional probability.  

1.

You roll two dice.  The first die shows a ONE and the other die rolls under the table and you cannot see it.  Now, what is the probability that both die show ONE? 

Choose:

1 : 3
1 : 6
1 : 36
9 : 36

 

 

2. You decide to tell your fortune by drawing two cards from a standard deck of 52 cards.  What is the probability of drawing two cards of the same suite in a row?  The cards are not replaced in the deck.

Choose:

13/52
12/51
13/51
12/52

 

 

 

3.

A new bag of golf tees contains 10 red tees, 10 orange tees, 10 green tees and 10 blue tees.  You empty the tees into your golf bag.  What is the probability of grabbing out two tees of the same color in a row for you and your partner?

Choose: 

1/40
10/40
9/39
9/40

 

 

4.

In a library box, there are 8 novels, 8 biographies, and 8 war history books.  If Jack selects two books at random, what is the probability of selecting two different kinds of books in a row?  

Choose:

16/23
16/24
8/24
7/23

 

 

 

5.

What is the probability that the sum of two die will be greater than 8, given that the first die is 6?

Choose:

1/2
3/4
2/3
7/12

 

 

 

6.

What is the probability of drawing two aces from a standard deck of cards, given that the first card is an ace?
The cards are not returned to the deck.  

Choose:

1/663
1/221
4/52
3/51

 

 

 

7.

A new superman MasterCard has been issued to 2000 customers.  Of these customers, 1500 hold a Visa card, 500 hold an American Express card and 40 hold a Visa card and an American Express card.  Find the probability that a customer chosen at random holds a Visa card, given that the customer holds an American Express card.

Choose:

1/4
1/3
2/25
1/50

 

 

8.

A survey of middle school students asked:  What is your favorite winter sport?  The results are summarized below:
 

                      Favorite Winter Sport

Grade Snowboarding Skiing Ice Skating TOTAL
6th 68 41 46 155
7th 84 56 70 210
8th 59 74 47 180
TOTAL 211 171 163 545

Using these 545 students as the sample space, a student from this study is randomly selected. 

a.) What is the probability of selecting a student whose favorite sport is skiing?
b.) What is the probability of selecting a 6th grade student?
c.) If the student selected is a 7th grade student, what is the probability that the student prefers ice-skating?
d.) If the student selected prefers snowboarding, what is the probability that the student is a 6th grade student?
e.)  If the student selected is an 8th grade student, what is the probability that the student prefers skiing or ice-skating?