Question

1. A bag contains 5 red marbles and 4 green marbles.

What is the probability of choosing a red marble then a green marble, without replacement?
25/81
20/81
5/18
25/72

2. Adam, Jack and Sheila are the three seniors who have been elected to student council. The president and vice president are randomly selected from these three seniors by drawing their names from a hat.

What is the probability that Jack will be selected first for president and Sheila will be selected second for vice president?
5/6
1/9
2/3
1/6

3. John rolls a six-sided number cube twice.

What is the probability of getting an even number and then an odd number?
1/2
1/6
5/6
1/4

4. On a true-false quiz of six questions, Karen answers all the questions.

What is the probability that she answers the first three questions correctly and the last three questions incorrectly?
1/8
1/64
1/32
1/4

Answer 1

1) probability=number of specific outcomes/number of possible outcomes.

probability of two events occurring is the product of the two probabilities.

So without replacement:

P(RandG)=(5/9)*(4/8)=5/18

2)

P(JandS)=(1/3)(1/2)=1/6

3)

P(EandO)=(1/2)(1/2)=1/4

4)

P(3Cand3I)=(1/2)(1/2)(1/2)(1/2)(1/2)(1/2)=(1/2)^6=1/64