Ratios and Rates. ratio – is a comparison of two numbers or more values. Example: 1:3.
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Transcript of Ratios and Rates. ratio – is a comparison of two numbers or more values. Example: 1:3.
Ratios and Rates
Ratios and Rates
ratio – is a comparison of two numbers or more values.
Example:
1:3
EXAMPLE:
IF WE COMPARE THE NUMBER OF GIRLS WITH THE NUMBER OF BOYS
WE CAN SAY THAT:
THERE IS 1 BOY AND 3 GIRLS , SO:
(FOR EVERY ONE BOY THERE ARE 3 GIRLS)
OR
(THERE ARE 3 GIRLS FOR EVERY ONE BOY)
)
1 : 3
3 : 1
Ratios and RatesThe order of the numbers in a ratio should match the order of the words in a ratio.
apples to oranges
2 to 3
Ratios and RatesRatios can be written in 3
different ways.
3 to 1
3 : 1
3/1
red to black
Ratios and RatesRatios can show comparisons
between:
a) part to partred to green
1 to 2green to red
2 to 1
Ratios and RatesRatios can show comparisons between:
b) part to whole
red to whole
1 to 3
green to whole
2 to 3
Ratios and RatesRatios can show comparisons between:c) whole to part
whole to red
3 to 1
whole to green
3 to 2
Ratios and Rates
Compare octagon to all shapes
1 to 8 1 : 8
1/8
Ratios and RatesCompare all shapes to trapezoid
8 to 1 8 : 1 8/1
Ratios and RatesCompare pentagons to hexagons
2 to 3 2 : 3 2/3
NOW, SOME EXERCISES
Ratios and Rates
Give each ratio in three forms.8 roses out of 24 flowers
24
8
3 dogs out of 12 animals
3 : 12
SOLVE
1) In the following diagram
What is the ratio of orange squares to white squares?
2. WHAT IS THE RATIO OF GREEN BALLS TO RED BALLS?
3. A CLASS OF 32 STUDENTS HAS 12 GIRLS. WHAT IS THE RATIO OF GIRLS TO BOYS?
GIVE EACH RATIO BY SHOWING COMPARISONS BETWEEN :
Part to part
Part to whole
Whole to part
Equivalent RatiosYou can have equivalent ratios by dividing or multiplying the numerator and denominator by by the same value
24
8 ÷ 8
÷ 8=
3
1
4 : 5 is the same as 4×2 : 5×2 = 8
: 10
EXAMPLE: A Recipe for pancakes uses 3 cups of flour
and 2 cups of milk. So the ratio of flour to milk is 3 : 2 To make pancakes for a LOT of people we
might need 4 times the quantity, so we multiply the numbers by 4:
3×4 : 2×4 = 12 : 8 In other words, 12 cups of flour and 8
cups of milk. The ratio is still the same, so the pancakes
should be just as yummy.
Rate – It is a ratio that compares different kinds of units by division to obtain a
unit rate or rate per unit.
Rate
To express a ratio as a rate per unit (1), write the ratio as a fraction and then divide the numerator by the denominator.
395 miles in 5 hours
5
395=
79 miles per hour
miles
hours 1
? miles
hours
Ratios and RatesExpress each ratio as a rate.5 inches of rain in 30 days
30
5=6
1inch of rain per day
120 words in 3 minutes
3
120=
40 words per minute1
? wordsper minute
÷ 5
÷ 5