Proportions Practice

Front

What is a proportion?

Back

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

Front

How do you determine if two ratios form a proportion?

Back

Two ratios form a proportion if the cross products are equal.

Front

What is the cross product of the ratios \( \frac{a}{b} \) and \( \frac{c}{d} \)?

Back

The cross product is \( a \times d \) and \( b \times c \). If \( a \times d = b \times c \), then the ratios form a proportion.

Front

If \( \frac{x}{8} = \frac{25}{40} \), how do you solve for x?

Back

Cross multiply: \( 40x = 200 \). Then, divide by 40 to find \( x = 5 \).

Front

What is the scale of a map?

Back

A scale is a ratio that compares a distance on the map to the actual distance it represents.

Front

If a map has a scale of 1 cm : 13 km, how do you find the distance between two cities on the map?

Back

Divide the actual distance by the scale factor. For 104 km, it would be \( \frac{104}{13} = 8 \) cm.

Front

How many quarts are in a gallon?

Back

There are 4 quarts in 1 gallon.

Front

If a cafeteria manager buys 25 gallons of milk, how many quarts is that?

Back

Multiply the number of gallons by 4: \( 25 \times 4 = 100 \) quarts.

Front

What is the formula to solve for x in a proportion?

Back

Use cross multiplication: If \( \frac{a}{b} = \frac{x}{c} \), then \( a \times c = b \times x \).

Front

If \( \frac{2}{5} = \frac{x}{65} \), how do you solve for x?

Back

Cross multiply: \( 2 \times 65 = 5x \). Then, solve for x: \( x = 26 \).