Unit E: Statistics and Probability

Chapter 2: Probability

Practice

Instructions: Click the Download File button to download a printable PDF of the questions. Answer each of the following practice questions on a separate piece of paper. Step by step solutions are provided under the Solutions tab. You will learn the material more thoroughly if you complete the questions before checking the answers.

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Practice
Solutions

In the following chart, each probability is expressed as a fraction. Convert the probability to a decimal, percent, ratio, and statement.

Fraction	Decimal	Percent	Ratio	Statement
$\frac{7}{8}$
$\frac{79}{100}$
$\frac{3}{7}$

Trevor has 249 songs on his phone. There are 53 country, 67 rock, 81 pop, and 48 rap songs.
1. What is the probability that the first song played is a country song? Express your answer as a fraction and as a percent.
2. What is the probability that the first song played is a rock song? Express your answer as a ratio.
3. What is the probability that the first song played is a pop or rap song? Express your answer as a statement.

Question 1

In the following chart, each probability is expressed as a fraction. Convert the probability to a decimal, percent, ratio, and statement.

Fraction	Decimal	Percent	Ratio	Statement
$\frac{7}{8}$
$\frac{79}{100}$
$\frac{3}{7}$

Solution

Fraction	Decimal	Percent	Ratio	Statement
$\frac{7}{8}$	$\frac{7}{8} = 0.875$	$\frac{7}{8} \times 100 % = 87.5 %$	7:8 The numerator is written first. The numerator and denominator are separated by a colon.	7 to 8 The numerator is written first. The numerator and denominator are separated by the word to.
$\frac{79}{100}$	$\frac{79}{100} = 0.79$	$\frac{79}{100} \times 100 % = 79 %$	79:100	79 to 100
$\frac{3}{7}$	$\frac{3}{7} = 0.429$	$\frac{3}{7} \times 100 % = 42.9 %$	3:7	3 to 7

Question 2

Trevor has 249 songs on his phone. There are 53 country, 67 rock, 81 pop, and 48 rap songs.

What is the probability that the first song played is a country song? Express your answer as a fraction and as a percent.
What is the probability that the first song played is a rock song? Express your answer as a ratio.
What is the probability that the first song played is a pop or rap song? Express your answer as a statement.

Solutions

$\begin{array}{rcl} probability & = & \frac{number of country songs}{total number of songs} \\ = & \frac{53}{249} \end{array}$

The probability written as a fraction is $\frac{53}{249}$ .

The probability written as a percent is $\frac{53}{249} \times 100 % = 21.3 %$ .
$\begin{array}{rcl} probability & = & \frac{number of rock songs}{total number of songs} \\ = & \frac{67}{249} \end{array}$

The probability written as a ratio is 67:249.
$\begin{array}{rcl} probability & = & \frac{number of pop songs + number of rap songs}{total number of songs} \\ = & \frac{81 + 48}{249} \\ = & \frac{129}{249} \end{array}$

The probability that the first song played is either a pop song or a rap song is 129 to 249.