Warm UpDivide. Round answers to the nearest tenth.
1. 2.
3. 4.
23.3 3.5
23.8 23.9
420 18
73 21
380 16
430 18
Ratio: 903
Rate: 90 miles3 hours
...as a ratio like this,
A rate is a comparison of two quantities measured in different units.
For example, the phrase “90 miles per 3 hours” can be written...
...or as a rate, like this
Unit rates are rates in which the second quantity is 1.
unit rate: 30 miles,1 hour
or 30 mi/h
The ratio 903
can also be simplified by dividing:
903
= 301
Class Example
Geoff can type 30 words in half a minute. How many words can he type in 1 minute?
Write as a rate.
=
Geoff can type 60 words in one minute.
Multiply to find words per minute.
60 words 1 minute
30 words minute
12
30 words • 2 minute • 212
Partner Practice
Penelope can type 90 words in 2 minutes. How many words can she type in 1 minute?
90 words 2 minutes
Write a rate.
=
Penelope can type 45 words in one minute.
90 words ÷ 2 2 minutes ÷ 2
Divide to find words per minute.
45 words 1 minute
Individual Practice
A piece of gold with a volume of 0.5 cubic meters weighs 9650 kilograms. What is the density of gold?
Gold has a density of 19,300 kg/m3.
9650 kg0.5 m3
Write the rate.
Multiply to find kilograms per 1 m3.
9650 kg • 20.5 m3 • 2
19,300 kg1 m3
To estimate is to find a value that is close to the actual value, but not necessarily the true value.
Estimate the unit rate.
Partner Practice
313 Is not divisible by 8, so choose a number close to 313 that is divisible by 8.
313 feet in 8 seconds
313 feet to 8 seconds is approximately 40 feet per second.
313 feet8 seconds
320 feet8 seconds
40 feet1 second
Divide to find feet per second.
Estimate each unit rate.
Individual Practice
Choose a number close to 583 that is divisible by 85.
583 soccer players to 85 soccer balls.
583 soccer players to 85 soccer balls is approximately 7 players per soccer ball.
583 players85 soccer balls
595 players85 soccer balls
7 players1 soccer ball
Divide to find players per soccer ball.
Pens can be purchased in a 5-pack for $1.95 or a 15-pack for $6.20. Which pack has the lower unit price?
Class Practice
Set up proportions for both situations.price for package
number of pens =$1.95
5= $0.39
price for packagenumber of pens
= $6.2015
$0.41
The 5-pack for $1.95 has the lower unit price.
Divide the price by the number of pens.
Compare to determine your answer.
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