Question

The graph shows the relationship between the weight of organic soap and its cost. Which of the given options is true?

• A. The equivalent weight of $\$1$ soap is $0.2oz.$
• B. The cost of $4.5oz$ soap is $\$18.$
• C. The cost of the soap is $\$5/oz$
• D. $100oz$ soap would cost $\$480.$

Answer 1

The correct option is B The cost of $4.5oz$ soap is $\$18.$

The graph is a straight line passing through the origin; hence, it represents a proportional relationship.
Let us consider two points on the line,
$x_1=3.5,y_1=14;x_2=7.5,y_2=30$

The unit rate/slope $=\frac{\text{Rise}}{\text{Run}}=\frac{y_2-y_1}{x_2-x_1}=\frac{30-14}{7.5-3.5}=\frac{16}{4}=\$4/oz$
Option A is false.

Weight of $\$4$ soap $=1oz$
Weight of $\$1$ soap $=14oz=0.25oz$
Option B is false.

Cost of $100oz$ soap $=100\times 4=\$400$
Option C is false.

Cost of $4.5oz$ soap $=4.5\times 4=\$18$
Option D is true.