Proportional Relationships

Three friends are buying seashells at the gift shop on the beach. Melanie buys 2 seashells for​ $0.80. Rosi buys 5 seashells for​ $2.00. Carlos buys 4 seashells for​ $1.60. Which graph represents the situation?

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Three friends are buying seashells at the gift shop on the beach. Melanie buys 2 seashells for​ $0.80. Rosi buys 5 seashells for​ $2.00. Carlos buys 4 seashells for​ $1.60. What is the constant of proportionality if one exists?

• $0.40

• $0.80

• $1.60

• Not a proportional relationship

Which of these graphs shows a relationship that is NOT​ proportional? Mark all that apply.

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The graph shows the relationship between the distance a taxi travels and the cost of the taxi ride. Is the relationship​ proportional? Explain. What is true about the graph?

• The relationship is not proportional because the graph does not pass through the origin.

• The relationship is not proportional because the graph is not a straight line.

• The relationship is proportional because the cost increases as the distance increases.

• The relationship is proportional because the graph is a straight line.

The graph shows a proportional relationship between a​ family's distance from home and the time they spent driving. What is the constant of​ proportionality? What does the point​ (1,49) represent?

• The distance to the destination.

• The time driven on the vacation.

• 49 hours and being 1 mile from home.

• 1 hour and being 49 miles from home.

The graph shows a proportional relationship between a​ family's distance from home and the time they spent driving. What is the constant of​ proportionality?

• 1/65

• 65

• 1/49

• 49

Error Analysis: You and a friend look at the graph. Your friend incorrectly says the constant of proportionality of y to x is 1/18. Find the correct constant of proportionality. What is your​ friend's likely​ error?

• Your friend found x/y.

• Your friend found x−y.

• Your friend found x•y.

• Your friend found x+y.

In a certain​ city, there are two stores where you can rent DVDs. The table shows the cost y in dollars to rent x DVDs at store A. The graph represents the cost at store B. At which store is the cost of renting DVDs the​ least and what is the constant of proportionality?

• Store A: $3.15

• Store A: $3.20

• Store B: $3.20

• Store B: $3.15

Does the graph show a proportional relationship between x and​ y?

• No, because the graph does not pass through the origin.

• Yes, because the graph passes through the origin.

• ​Yes, because the graph is a straight line.

• No, because the graph is not a straight line.

The graph shows the relationship between the weight of silver and the total cost. Which of the following is​ true? Mark all that apply.

• The point​ (0,0) means that 0 pounds of silver cost​ $0.00.

• The point​ (4,68) means that​ $4.00 is the cost for 68 pounds of silver..

• ​The point​ (1,17) shows the constant of proportionality.

• The graph shows a proportional relationship.

• The point​ (2,34) means that 2 pounds of silver cost​ $34.