Constant of Proportionality
Grade 7 · Math · Proportional Relationships · South Dakota, USA
Lesson Summary
Find the constant that links two proportional quantities and use it to solve problems.
Explanation
When two quantities are proportional, you can always multiply one by a fixed number to get the other. That fixed number is called the constant of proportionality, often written as k in the equation y = kx. For example, if every hour of work earns $12, then k = 12 and earnings = 12 × hours. Finding k lets you predict one quantity when you know the other.
Practice Questions
Q1: A car travels 180 miles in 3 hours at a constant speed. What is the constant of proportionality?
Answer: k = 180 ÷ 3 = 60. The constant of proportionality is 60 miles per hour.
Q2: If y = kx and y = 35 when x = 5, find k and then find y when x = 9.
Answer: k = 35 ÷ 5 = 7. When x = 9, y = 7 × 9 = 63.
Q3: A recipe uses 2 cups of flour for every 3 cups of sugar. What is the constant of proportionality of flour to sugar?
Answer: k = 2/3. For every cup of sugar, you need 2/3 cup of flour.
People Also Ask
What is Constant of Proportionality in Grade 7 Math?+
Constant of Proportionality is a lesson in the Proportional Relationships chapter of Grade 7 Math. It is part of the South Dakota, USA school curriculum and covers key concepts that students need to understand at this level.
What grade level covers Constant of Proportionality?+
Constant of Proportionality is taught in Grade 7 as part of the Math curriculum in South Dakota, USA.
How can I help my child with Proportional Relationships in Math?+
Start with the lesson summary and explanation on this page. Practice the questions provided, then use TutorTom for personalized, step-by-step help with Proportional Relationships topics.