Identifying Direct Proportion

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What is a direct proportion?

Back

A direct proportion is a relationship between two quantities where if one quantity increases, the other quantity increases at a constant rate. This can be expressed as y = kx, where k is the constant of proportionality.

Front

How do you find the constant of proportionality in a direct proportion equation?

Back

To find the constant of proportionality (k), rearrange the equation y = kx to k = y/x. This value remains constant for all pairs of (x, y) in a direct proportion.

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Back

Front

If 2 slices of pizza have 300 calories, how many calories are in 6 slices?

Back

900 calories.

Front

In a cake recipe, if 1.5 cups of milk are needed for 3 cups of flour, how much milk is needed for 12 cups of flour?

Back

6 cups of milk.

Front

How can you determine if a table represents a direct proportion?

Back

You check ALL of the ratios of y/x or output/input to ensure they are equivalent to the same number.

Front

What is the constant of proportionality if the table shows that y/x = 1/2?

Back

The constant of proportionality is 1/2.

Front

What is the relationship between the variables in a direct proportion?

Back

In a direct proportion, the ratio of the two variables remains constant.

Front

If y = 4x, what is the constant of proportionality?

Back

The constant of proportionality is 4.

Front

If a recipe is doubled, how does that affect the quantities of ingredients?

Back

All quantities of ingredients must also be doubled to maintain the proportions.