Transcript Exploring Ratios
Exploring Ratios
On her bird watching expedition, Cassie spotted 6 robins and 3 bluebirds sitting on a fence. Here are some ways she compared the birds: Number of robins compared to number of bluebirds: 6 robins to 3 bluebirds Number of bluebirds compared to number of robins: 3 bluebirds to 6 robins Number of robins compared to total number of birds: 6 robins to 9 birds
Cassie could have also compared the birds using fractions. (Remember there were 6 robins and 3 bluebirds) What fraction of the total number of birds were robins? 6 9 What fraction of the total number of birds were bluebirds? 3 9
What is ratio?
A
ratio
is a comparison of 2 quantities with the same unit.
Rabbits…
Mark has 4 brown rabbits and 5 white rabbits.
We can use ratio to compare the numbers of brown and white rabbits.
For example – the ratio of brown rabbits to white rabbits is 4 brown rabbits to 5 white rabbits.
The ratio is 4 to 5 and is also written as 4 : 5
More practice…
The ratio of white to brown rabbits is… 5 to 4, or 5 : 4 These are called
part-to-part
ratios (because they are comparing two parts of a whole) The numbers 4 and 5 are the
terms of the ratio
Order is important in ratio. 5 : 4 is
NOT
the same as 4 : 5
Still more practice…
You can also compare the parts to the whole.
Here are some other ratios you can use to compare the rabbits.
Brown rabbits to all the rabbits: White rabbits to all the rabbits: 4 to 9 or 4 : 9 or 4 9 5 to 9 or 5 : 9 or 5 9 These are called
part-to-whole
ratios (because they are comparing a part to the whole)
Part-to-whole ratios are often written as fractions. 4 to 9, or 4 : 9 is also 4 9 When we read a ratio that is written as a fraction, we say “four to nine”
Try these…
Write each ratio 2 ways a) apples to pears 4 to 3 , 4 : 3 b) caps to shoes 5 to 6 , 5 : 6 c) roses to daisies 1 to 4 , 1 : 4
And these…
Write a ratio to show the numbers of: a) ladybugs to ants b) c) d) ants to ladybugs ladybugs to insects ants to insects 3 to 7 , 3 : 7 7 to 3 , 7 : 3 3 3 to 10, 3 : 10, 10 7 to 10, 7 : 10, 7 10