Solving 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 terms and then solve for the unknown variable.

Front

What does cross-multiplication mean?

Back

Cross-multiplication involves multiplying the numerator of one ratio by the denominator of the other ratio.

Front

If 4/8 = x/16, what is x?

Back

x = 8 (Cross-multiply: 4 * 16 = 8 * 8).

Front

In a proportion, if one ratio increases, what happens to the other ratio?

Back

If one ratio increases, the other ratio must also increase to maintain the equality.

Front

What is the formula for finding the cost per person?

Back

Cost per person = Total cost / Number of people.

Front

If 6 people pay $39, what is the cost per person?

Back

Cost per person = $39 / 6 = $6.50.

Front

How do you find the total cost for a different number of people?

Back

Total cost = Cost per person * Number of people.

Front

If Sara types 90 words in 4 minutes, how many words does she type in 1 minute?

Back

Words per minute = 90 words / 4 minutes = 22.5 words per minute.

Front

If Sara types 22.5 words per minute, how many words can she type in 10 minutes?

Back

Words in 10 minutes = 22.5 words/minute * 10 minutes = 225 words.