4-2 Rates

A rate is a type of ratio, but we are comparing 2 completely different items. Like distance and speed, cars to houses or veggies to meat.• Ex:• 60 miles PER hour• 2 cars PER house• 3 veggies PER meat• $2.00 PER 10 ounces

To find a UNIT rate, you set up a ratio and reduce it as low as it can go.• Using the last example of $2.00 for 10 ounces,

how much would EACH ounce cost? The unit rate is $2.00 / 10 ounces.• Reduce it by dividing to and bottom of the

fraction by a number that goes into both….a 10 will go into both:

$2.00/10 = $.20/1

This means that each ounce would cost $.20

How do you know what number goes on the bottom?•The UNIT that you are trying to solve for will go on the BOTTOM of the fraction.•We were trying to find the cost for each OUNCE…so ounces go on the bottom.

Comparing Unit Rates

A pack of 5 pencils cost $1.50. A pack of 10 pencils cost $2.70. Which is the better deal? To compare the two, you need to know the cost of each pencil. So how do we set up the two ratios?

Since we are looking for the PENCIL as our unit, the number of pencils would go on the bottom of our ratios:

$1.50 / 5 and $2.70 / 10

Now you reduce the fractions until the bottom number is a 1!!!

You do this by dividing….remember the top guy of the fraction goes “in the box” _____ _____

5 ) 1.50 10 ) 2.70

When you do the math, you get

$.30/1 for the 5 pack and $.27/1 for the 10 pack.

Which pack is the better deal?

Homework:

1)A recipe to make 10 muffins calls for 360 grams of flour. How many grams of flour are in each muffin?

2)It takes 270 minutes to cook an 18 pound turkey. How many minutes per pound did it take to cook the turkey.