4.1 d - unit rates lesson 4-1 d mrs. wilson. what does rate mean? the unit rate is the rate for one...
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4.1 D
- UNIT
RATES
LESS
ON 4-1
D
MRS. W
ILSON
WHAT DOES RATE MEAN?
The unit rate is the rate for one unit of a given quantity. Unit rates have a denominator of 1.
The word PER means 1 !!!!
A rate is a RATIO that compares two things that have DIFFERENT units!
Ex: Students per Bus OR Miles per Hour
GOING FROM RATE TO UNIT RATE
Rate: 150 heartbeats2 minutes
just DIVIDE to get the Unit Rate!!!
150 ÷ 2 = 75 heartbeats per minute.
See how there are 2 different units of measure?
150 heartbeats in 2 minutes
You can also write it as…
75 heartbeats / minute
FIND THE UNIT RATEAmy can read 88 pages in 4 hours. What is the unit rate?
(How many pages can she read per hour?)
88 pages4 hours
88 ÷ 4 = 22
So…
22 pages per hour
or 22 pgs / hr
1 hr
Notice that hours turns to 1…that is the number you divide by!
NOT ALL RATES WILL BE EVEN NUMBERS!
It is $30 for 4 t-shirts. What is the unit rate?
$30 4 shirts
30 ÷ 4 = 7.5
You have to add a decimal and a zero!!
How much $ is this?
1 shirt
$7.50 for each shirt!
SOMETIMES YOU KNOW THE UNIT RATE ALREADY…
Joe’s car goes 20 miles per gallon of gasoline. How far can it go on
8 gallons of gasoline?
20 miles1 gallon
*Per Means 1.
Here’s what it looks like!
=8 gallons
x 8x 8
x 8x 8
20 x 8 = 160. Joe’s car can go 160 miles on 8 gallons of gas.
SOMETIMES YOU KNOW THE UNIT RATE ALREADY…
It costs $15.50 per student for the trip. If there are 20 students going, how
much will the total be?
$15.50 1 student
*Per Means 1.
Here’s what it looks like!
=20 students
x 20x 20
x 20x 20
15.50 x 20 = 310. So it will cost $310 for 20 students to go.
It’s easy to remember:
If you need to FIND a UNIT rate, you DIVIDE
If you already KNOW the Unit Rate, you MULTIPLYIf you are ever unsure WHICH number to divide by, find the measure that will become a 1. This measure is what you divide by!!!