Roger likes to eat Crunchy Flakes cereal for breakfast every morning. Crunchy...

[MichaeThomas]

...Flakes comes in a 20-ounce box? that costs $4.20 and a30unce box that costs $6.00. Explain which box of cereal is the better buy

 

[chris]

well, just looking at those two amounts, you can tell that 30 oz. is half again as much as 20 oz. or 50% more oz. 20 + 10 = 30. so therefore how much is another half of the cost of 20 oz. that would be $2.10 more, plus the 20 oz is $6.30 per 30 oz. vs. $6.00 for the 30 oz. box. so you can see the bigger box is a better value.

of course, if you want to break it down by per oz. price, divide $4.20 by 20 oz, and you get 21 cents per oz. vs. 20 cents per oz for the 30 oz box.