Proportions

Front

What is a proportion?

Back

A proportion is an equation that states that two ratios are equal.

Front

How do you solve a proportion?

Back

To solve a proportion, cross-multiply the two ratios and set the products equal to each other.

Front

What is a ratio?

Back

A ratio is a comparison of two quantities, showing how many times one value contains or is contained within the other.

Front

If the ratio of boys to girls is 3 to 2, how many girls are there if there are 12 boys?

Back

8 girls.

Front

What is the formula for finding a missing value in a proportion?

Back

If a/b = c/d, then ad = bc.

Front

If 150 people wait 20 minutes, how long will 1200 people wait?

Back

160 minutes.

Front

What is the relationship between the size of a bottle and how long it lasts?

Back

Larger bottles generally last longer if the usage rate is constant.

Front

If a 12-ounce shampoo bottle lasts 16 weeks, how long will an 18-ounce bottle last?

Back

24 weeks.

Front

How do you calculate the cost of refreshments for a different number of guests?

Back

Use the unit rate to find the cost per guest and multiply by the new number of guests.

Front

If it costs $9.50 for 10 guests, how much for 80 guests?

Back

$76.