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(6-1) Ratios and Unit Rate
Ratio – a comparison of 2 numbers by division.
Ex: 8 out of 23 students have blue eyes.
15 out of 23 students do not have blue eyes
So… the RATIO of blue to non-blue eyes is
8 to 15!!! This is a RATIO! It looks like 8:15!!!
Ex: Out of 120 students, 60 of them get free lunch.
What is the ratio of students who get free lunch to the total number of
students??
60_ = _1_
120
2
Ex: 3 feet to 16 inches uh oh!! Different units!! You have to make them the
same!!! Go with INCHES!!
3 feet is the same as 36 inches, so…
__36__ = __9__
16
4
Rate – a ratio of 2 measurements that have different
units.
Keywords for RATE:
*per
*costs
*out of
*in
* of/to
Unit Rate – a rate that is simplified so that the
denominator is 1!!
Examples of Unit Rate –
*Dollars per pound (that’s one pound!!)
* Miles per gallon (that’s one gallon!!)
* Beats per minute (that’s one minute!!)
Example ~ Find the Unit Rate:
1. $3.95 for 5 pounds of bananas ~ How much per pound? (one pound)
3.95 ÷ 5 = 0.79
So the unit rate would be $0.79 per pound
2. 100 feet in 14.5 seconds ~ How many feet per second? (one second)
100 ÷ 14.5 = 6.90 feet per second
3.
A package of 20 recordable CDs costs $18, and a package of 35
recordable CDs cost $22. Which package has the lowest cost per CD?
18 ÷ 20 = 0.90 per CD
22 ÷ 35 = 0.63 per CD
So the unit rate for 35 CDs at $22 is the lower cost per CD.