A
It should be the 90 pack container. You should see the difference in buying that as opposed to the 2 smaller containers. Usually stores make you think that way, but sometimes they pull a fast one and make the lower content container the better buy. You should ALWAYS shop with a calculator. I'll give you an example. Suppose the packs are listed as below
Number packs Price Unit Price
30 pack 8.99 30 cents rounded
60 pack 17.00 28.33
90 pack 23.00 25.55
This one worked as it should. It's fair to the consumer and it's actually fair to the merchant and the manufacturer.
B
The answer to B is what I actually did to get the answers for A
20 5.49
Unit Cost = Total Cost divided by number in the container.
Unit Cost = 5.49/20 = 0.2745 dollars or 27 cents.
C
Done the same way as B
Unit Cost = 10.97/ 60 = 0.1828 dollars which rounds to 28 cents.
D
Unit Cost = 18.95/90 = .211 dollars = 21 cents. This is an example of when the merchant is trying to persuade you to buy something that is not the best buy. And they do that.
E
I will let you answer this yourself. Education is meant to make you wise in what you do. This question is something you should become familiar with. Don't just buy something. Unit cost it. It takes longer but you are saving money and you'd be surprised what you save at the end of a year.