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Chapter 4 · Ratios · page 19 of 68

Ratios and simplest form

levelPre-algebra
standard6.RP.A.1
practiceRatios and rates

A ratio compares two amounts, in a fixed order. 8 boys to 12 girls is 8:12, and 8:12 simplifies like a fraction to 2:3. The first thing named goes first. Switching the order says something different.

How to use it

  1. Write the amounts in the order the question names them.
  2. Divide both by their greatest common factor.
  3. Part to whole: the second number is the total of all the parts.

Example

8:12=2:38 : 12 = 2 : 3
boys to all: 8:20=2:5\text{boys to all: } 8 : 20 = 2 : 5
12:8=3:2 is girls to boys12 : 8 = 3 : 2 \text{ is girls to boys}

Where it goes wrong

  • Flipping the order.
  • Comparing a part to the other part when the question asks part to whole.

Related

Equivalent fractions and simplest formUnit ratesProportions and cross multiplying
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