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 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? What fraction of the total number of birds were bluebirds?

A ratio is a comparison of 2 quantities with the same unit. 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: These are called part-to-whole ratios (because they are comparing a part to the whole) 4 to 9 or 4 : 9 or 5 to 9 or 5 : 9 or

Part-to-whole ratios are often written as fractions. 4 to 9, or 4 : 9 is also When we read a ratio that is written as a fraction, we say “four to nine”

Try these… Write each ratio 2 ways apples to pears caps to shoes roses to daisies 4 to 3 , 4 : 3 5 to 6 , 5 : 6 1 to 4 , 1 : 4

And these… Write a ratio to show the numbers of: ladybugs to ants ants to ladybugs ladybugs to insects ants to insects 3 to 7 , 3 : 7 7 to 3 , 7 : 3 3 to 10, 3 : 10, 7 to 10, 7 : 10,

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