CALCULATING UNIT RATES

Which one is the better buy?
By: Jadyn Lopez

I am going to find two items with different deals involving the amount something costs per how much of the item there is.  Then I am going to calculate the unit rate.

Margaret went to the store and saw a deal for three bottles of Garnier Fructis shampoo for $9.75.

1. Set up the unit rate so you know what you're looking for, you are looking for the price PER item.

Margaret went to the store and saw a deal for three bottles of Garnier Fructis shampoo for 9.

She then looked to her right and saw 7 bottles of Tresemme shampoo for 10.17.  Which set should Margaret buy?

To figure out which set she should buy, you would have to calculate the unit rate.

Here's how you do it!

1. Set up the unit rate so you know what you're looking for, you are looking for the price per item.

3 items  - $9.75   1 item - ?

2.  Divide the price by the number of items to get the price per item.

$9.75 divided by 3 = $3.75

3.  3 items - $9.75   1 item - $3.25

Then, just repeat the process with the other item. 

1.  10 items - $12.17    1 item - ?

2.   $12.17 divided by 10 = $1.11

3.   10 items - $12.17   1 item - $1.11

THE TRESEMME SHAMPOO IS THE BETTER BUY!! That's the brand that Margaret should purchase because it is less per bottles than the Garnier Fructis!

Why is calculating the unit rate helpful?

Calculating the unit rate is helpful because it tells you the amount per an item.  So if you get multiple items for one price, you can just use a proportion to find the cost of just one item. 

Comment Stream