7th Grade Math 7.4(A)

A dog eats 1.25 cups of dog food twice a day. Create a graph that best represents this relationship of x, the number of days and y, the number of cups of dog food.

Answer explanation

Since the the dog eats 1.25 cups of dog food twice a day the constant of proportionality would be 2.50 cups of dog food every 1 day. So we could pick the point where x is 2 and y is 5. Then we can just divide y by x or 5/2 which gives us our constant of proportionality of 2.50 or 2.5.

Natasha has a job putting letters in envelopes to be mailed. In 1 hour she put 42 letters in envelopes. Write an equation best represents y, the total number of letters Natasha puts in envelopes in x hours if she continues at this rate.

Mathematical Equivalence

ON

Answer explanation

Since the constant of proportionality is 42 letters in 1 hour we can just multiply x by 42 to get y, the total number of leters Natasha puts in envelopes for ay gven amount of hours.

Pamela rode her bike at a constant rate of 0.1 kilometers per minute. Which x values will complete the table that represents the relationship between the number of minutes, x and the number of kilometers, y?

• 0.2, 0.3, 0.4

• 0.1, 0.1, 0.1

• 10.1, 15.1, 20.1

• 1.0, 1.5, 2.0

If a person burns 90 calories by climbing 18 flights of stairs, how many flights of stairs would they need to climb to burn 100 calories?

Mathematical Equivalence

ON

Answer explanation

The constant of proportionality is 5 calories for 1 flight of stairs. So all you would need to do is divide the calories by 5 and you would get the correct number of flights of stairs.

Cheddar cheese costs $4.25 per pound. Write an equation that represents y, the total cost of x pounds of cheddar cheese.

Mathematical Equivalence

ON

Answer explanation

The constant of proportionality is $4.25 every 1 pound, so you would just multiply x, the pounds of cheddar cheese by 4.25 to get y, the total cost.

(Use The Picture) Layla read ​ (a)   books in the first ​ (b)   months she was a member of the book club.

• 3
• 2
• 4
• 1
• 5
• 1.5
• 2/3

Which of these does NOT represent the distance a car travels when going 55 miles per hour?

• d=55t, where d represents distance in miles and t represents time in hours.

• 
• In 3 hours a car will travel a distance of 160 miles.

• 

Answer explanation

If the car travels at 55 miles per hour then it will travel 165 miles in 3 hours not 160 miles. You just have to multiply the hours by the 55 miles to get the total miles traveled since the constant of proportionality is 55 miles per hour.

An artist is making a scale model of a statue. On the model 2 inches represents 1 foot on the actual statue. create a graph that best represents this relationship.

Answer explanation

The constant of proportionality is 1 foot per every 2 inches which is 1/2 or 0.5. So the best point to plot would be when x is 8 and y is 4 because 4/8 is 1/2 or 0.5 which is the constant of proportionality.