Direct Proportionality: synchronized, one-way relationship between items
        a) as the number of items in a backpack increases, the weight of the backpack increases
        b) as the population of a city decreases, the amount of tax money collected decreases

Inverse Proportionality: synchronized, opposite relationship between items
        a) as the number of workers increases, the time needed to complete a project decreases
        b) as the amount of available food decreases, the number of hungry people increases

SAMPLE PRACTICE QUESTION FOR PROPORTIONS

1. If s is inversely proportional to y² and s = 1/4 when y = 1/2, then what is the non-negative value of y when s = 4?

      Solution
      A) First, find the change in s.
          s increased from 1/4 to 4, a 16-fold increase in s.
          s is inversely proportional to y², so y² must decrease by a factor of 16.

      B) Next, find y².
          original y = 1/2, so original y² = 1/4
          original y² = 1/4 --> new y² = (1/4) ÷ 16 = 1/64

      C) Finally, solve for new y.
          new y² = 1/64
          new y = √1/64 = 1/8

SAT Math: Proportion Problems

Lesson Includes:

—Math Terms for Proportions

—Sample Practice Questions

—Practice Questions

Math

SAT Reading

SAT Writing

SAT Vocabulary

PROPORTIONS MATH QUIZ

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