Direct proportion
Pages
Proportion as equality of ratios
Two pairs of quantities are in proportion when their ratios are equal.
Direct proportion
Direct proportion: multiply one quantity and the other multiplies the same way.
The unitary method
Finding the value of one unit first, then scaling up to any number of units.
Scaling a recipe
Scaling every ingredient by the same factor, and serving-size questions.
Best-buy comparisons
Comparing value by the price of one unit or the amount one penny buys.
Practice
Proportion as equality of ratios
Two pairs of quantities are in proportion when their ratios are equal.
PracticeDirect proportion
Direct proportion: multiply one quantity and the other multiplies the same way.
PracticeThe unitary method
Finding the value of one unit first, then scaling up to any number of units.
PracticeScaling a recipe
Scaling every ingredient by the same factor, and serving-size questions.
PracticeDirect and inverse proportion review
Direct and inverse proportion problems, and deciding which relationship holds.
PracticeRecipes and best buys review
Scaling recipes by awkward factors and comparing pack prices by a common unit.