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Probability Unit Study Guide
1.
2.
3.
Glenda has designed a spinner with blue, red, and green sections. The chances of spinning blue on
Glenda’s spinner are 50%, the chances of spinning red are 20%, and the chances of spinning green are
30%. Suppose you spin Glenda’s spinner 50 times,

How many times would you expect to spin blue?

How many times would you expect to spin red?

How many times would you expect to spin green?
Use the spinner at the right to answer the following questions.

What fraction of the area of the spinner is shaded gray?

What fraction is unshaded?

What fraction is marked with diagonal lines?

Suppose you spun the spinner 72 times. How many times would you expect to spin gray?
Unshaded region? Diagonal region?
A bucket contains 24 blue, green, red, and yellow blocks. The theoretical probabilities of drawing a
1
1
1
blue, green or red block are: P(blue) =
, P(green) = , and P(red) = .
12
8
3

How many blue blocks are in the bucket? Green? Red? Yellow?

What is the probability of drawing a yellow block?

What is the probability of not drawing a yellow block?
4.
At Hopkins High School, 135 students were
surveyed about their summer employment.
The results are shown in the Venn diagram.
What is the probability of selecting a student
at random who worked in retail?
5.
At Chisholm Trail Middle School, students who choose to take a music class may enroll in either band
or orchestra, but many not enroll in both classes. The table shows the number of students and their
music class selections. What is the probability that a student selected at random is female, given that the
student is in the orchestra?
6.
A couple is planning to have 3 children. How many different arrangements of girls and boys are
possible? Make a tree diagram to support your answer.
7.
Karen and Jake are playing a game of Rock-Paper-Scissors. Make a tree diagram to show the outcomes
and winners for each round.




Rock defeats scissors
Scissors defeats paper
Paper defeats rock
Both show the same shape is a tie
a.
What is the probability that Karen chooses paper?
b.
What is the probability that Karen chooses rock and Jake chooses paper?
c.
What is the probability that Karen wins the game?
d.
What is the probability that Jake wins the game?
e. What is the probability the game will end in a tie?
f.
IF Karen and Jake play the game 60 times, what is the predicted number of times that Karen will win?
8.
Karen’s little brother, Herb, has his arm in a cast, so he can only make the shapes for paper and scissors.
Karen’s little sister, Meg, is not old enough to make the shape for scissors, so she only plays with rock
and paper. Make an area model to show the possible outcomes for this game.
a.
What is the probability Meg will win?
b.
What is the probability Herb will win?
c.
Are Meg and Herb equally likely to win? Explain.
9.
Decide whether each statement is true or false. Justify your answers.

The probability of an outcome can be 0.

The probability of an outcome can be 1.

The probability of an outcome can be greater than 1.
10. Use the spinner to answer the following questions.
a.
What is the theoretical probability of spinning red? Blue?
Yellow?
b.
Suppose you spin 300 times, how many times do you expect to
land on blue?
c.
Is it equally likely that the pointer will land on each color? Explain.