Sat math Essentials

a.
3
4
2
b.
1
3
3
2
c.
1
3
5
2
d.
1
1
3
5
e.
1
4
3
Answer
b.
Probability is 
. Therefore, you can set up the following fraction:
1
3
3
2
Therefore, the probability of selecting a comedy DVD is 
1
3
3
2
.
13
13 + 4 + 15
number of comedy DVDs
total number of DVDs
number of specific outcomes
total number of possible outcomes
number of green buttons
total number of buttons
number of specific outcomes
total number of possible outcomes
number of specific outcomes
total number of possible outcomes
–
P R O B L E M S O LV I N G
–
1 6 9

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Multiple Probabilities
To find the probability that one of two or more mutually exclusive events will occur, add the probabilities of each
event occurring. For example, in the previous problem, if we wanted to find the probability of drawing either a
green or black button, we would add the probabilities together.
The probability of drawing a green button 
1
5
7
.
The probability of drawing a black button 
9
3
5
3
1
3
7
.
So the probability for selecting either a green or black button 
1
5
7
1
3
7
1
8
7
.
Practice Question 
At a farmers’ market, there is a barrel filled with apples. In the barrel are 40 Fuji apples, 24 Gala apples, 12
Red Delicious apples, 24 Golden Delicious, and 20 McIntosh apples. If a customer reaches into the barrel
and selects an apple without looking, what is the probability that she will pick a Fuji or a McIntosh apple?