Ratios: find one part when you know the total
Add the parts of the ratio to find the number of equal parts in the whole, then work out one group.
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The ratio of cats to dogs is 1 : 3. There are 20 pets in all. How many dogs are there?
Answer: 15
The ratio of guitars to drums is 4 : 1. There are 10 instruments in all. How many guitars are there?
Answer: 8
The ratio of pencils to pens is 2 : 4. There are 12 writing tools in all. How many pens are there?
Answer: 8
Tip: Add the parts of the ratio to find the number of equal parts in the whole, then work out one group.
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- Next in this topic Ratios: find the other group when you know one count Sixth Class
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- Mix It, Pace It: Ratio, Rate and Percent Grades 6–7 · printable lessons
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