Constant of Proportionality
Grade 7 · Math · Proportional Relationships · Texas, 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 Texas, 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 Texas, 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.