Question

The following graph shows the number of rolls of paper towels sold and their costs (in $). The cost difference between the two types of paper towels per roll is _______.

• A. $\$1.67$
• B. $\$2$
• C. $\$0.33$
• D. $\$1$

Answer 1

The correct option is C $\$0.33$

Type I:
$x_1=6,y_1=10;x_2=12,y_2=20$
Unit rate $=\frac{\text{Rise}}{\text{Run}}=\frac{y_2-y_1}{x_2-x_1}=\frac{20-10}{12-6}=\frac{10}{6}=\$53/roll$


Type II:
$x_1=5,y_1=10;x_2=10,y_2=20$
Unit rate $=\frac{\text{Rise}}{\text{Run}}=\frac{y_2-y_1}{x_2-x_1}=\frac{20-10}{10-5}=\frac{10}{5}=\$2/roll$

Cost difference per roll $=2-\frac{5}{3}=\frac{6-5}{3}=\frac{1}{3}\$0.33$