Proportionality question

Question

Willis has 2 paint supply stores.  Store A sells 2-gallon containers of paint for $58.  Store B sells 2-quart containers of paint for $14.50.  At each store, the cost of paint is in proportional relationship to the amount of paint.  

 

a) Find the constant of proportionality for store A in dollars per quart.

 

b)  which store is a better buy

Answer 1

Hello Heather,

 

I am glad you asked this question, because the process will be very helpful throughout life - especially if you go into the science!  Hint: If you learn simple concepts, you will not have to memorize a multitude of ideas.

 

First, I find that they want Store A's numbers in $/quart.

 

Store A: ($58/2 gallons) X (1 gallon/4 quarts) = ($/quart.)

 

Next, I find how much Store B is selling in $/quart.

 

Store B: ($14.50/2 quarts) = ($/quart)

 

Finally, compare Store A's ($/quart) to Store B's ($/quart) and you will have solved both parts of your problem.

 

So, What did you come up with?

Answer 2

For store A, you are given that the cost of paint is $58 per two-gallon container. One gallon is equal to four quarts. 

 

Therfore:

 

($58 / 2 gal.) × (2 gal. / 8 quarts) = $7.25 / quart 

 

At store B, the price is $14.50 per two-quart container. 

 

Thus:

 

$14.50 / 2 quarts = $7.25 / quart

 

Hence, both stores sell paint at the same price per quart.