Rates, Ratios and Proportions. a:b = c:d. What is a ratio?. A ratio is a comparison of two quantities that can be written as a to b, a : b , or . The quantities in the ratio are called terms. The first term in the ratio above is a , and the second term is b.
a:b = c:d
A ratio is a comparison of two quantities that can be written as
a to b, a:b, or .
The quantities in the ratio are called
terms. The first term in the ratio above is a, and the second term is b.
There are 8 boys to every 12 girls or 8:12 (8 to 12 ratio). This can also be written as the fraction 8/12.
8/12 is reduced to its simplest form of 2/3 and we can say that we have a 2:3, or 2 to 3, ratio of boys to girls.
Rates and Ratios
8 out of 20 students are boys
12 out of 20 students are girls
Just like when you find equivalent fractions!
Some Common Rates
• 22 miles per gallon
• 3 cups of water to 1 can of lemonade mix
• $1.50 per pound
• 72 heartbeats per minute
A rate is a special kind of ratio that compares two quantities with different units of measure. A common rate you already know is miles per hour. Some other examples of rates are shown below.
Rates often contain the word per, meaning for each or for every.
If the comparison is to 1 unit, the rate is called a unit rate .
When you compare unit rates, you can really see what is the faster rate or better buy because you are comparing one unit to one unit!
True Proportion Checklist
Same labels - across the top and bottom OR on the left and right side?
Equal Ratios? - You can use multiplication or division to create equal ratios or you may need to simplify one ratio and then compare to the other ratio to see!
Cross products equal?
A formula is a rule that uses symbols to relate two or more quantities.