Question

Ben needs to buy orange juice. He can buy 64 fl oz at the grocery store for $2.00, or he can buy 256 fl oz at the wholesale club for $7.50.

a) Find the unit price for the grocery store orange juice. Round your answer to the nearest thousandth.

b) Find the unit price for the wholesale club orange juice. Round your answer to the nearest thousandth.

c) Where should Ben buy the orange juice if he wants the best deal? Explain.

Answer 1

x - the price per oz in the grocery store
y - the price per oz in the wholesale club

a) The answer is $0.031 per oz
He can buy 64 fl oz at the grocery store for $2.00:
64x = 2
x = 2 / 64
x = $0.031

b) The answer is $0.029 per oz
He can buy 256 fl oz at the wholesale club for $7.50:
256y = 7.50
x = 7.50 / 256 
x = $0.029

c) The answer is wholesale club

Let's calculate where you can get more oz for $1 using the proportion.
Grocery store:
1 oz for $0.031
x oz for $1
1 : 0.031 = x : 1
x = 1 * 1 : 0.031
x = 32.26 oz

Wholesale club:
1 oz for $0.029
x oz for $1
1 : 0.029 = x : 1
x = 1 * 1 : 0.029
x = 34.48 oz

34.48 oz > 32.26 oz, so he should buy at the wholesale club