Exploring Ratios

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Exploring Ratios
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• 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

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• 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?

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What is ratio?

• A ratio is a comparison of 2 quantities with the
  same unit.

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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

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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

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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
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• 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

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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
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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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Assignment

• Page 304/305 3 - 10