Question

mathematics 7 - 7 - full year
5 - 5: lesson quiz
melanie buys 2 shells for $0.80. rosi buys 3 shells for $1.20. carlos buys 4 shells for $1.60. use the graph to determine whether there is a proportional relationship between the number of shells and their cost. if so, what does the constant of proportionality mean in this situation? use the drop - down menus to show and explain your answer.
gift shop shells
the relationship between the number of shells and their cost is choose...
the constant of proportionality means that each shell costs choose...
review progress
question 5 of 5

Explanation:

Step1: Calculate unit - cost for each case

For Melanie: $\frac{0.80}{2}=0.40$. For Rosi: $\frac{1.20}{3}=0.40$. For Carlos: $\frac{1.60}{4}=0.40$.

Step2: Check proportionality

Since the ratio of cost to number of shells is the same ($0.40$) for all cases and the graph is a straight - line through the origin, there is a proportional relationship.

Answer:

The relationship between the number of shells and their cost is: proportional.
The constant of proportionality means that each shell costs: $\$0.40$.