Practice Constant of Proportionality in Math

Use these practice problems to test your method after reviewing the concept explanation and worked examples.

Quick Recap

The constant ratio k between two proportional quantities: if y = kx, then k is the constant of proportionality.

If y is always 3 times x, the constant of proportionality is 3.

Example 1

easy
A car travels 60 miles per hour. Write the equation relating distance \(d\) and time \(t\). What is the constant of proportionality?

Example 2

medium
The table shows \(x\) and \(y\): (2, 10), (4, 20), (6, 30). Is this proportional? Find \(k\).

Example 3

easy
Apples cost \$0.75 each. Write the equation for cost \(C\) given quantity \(q\). Find the cost of 8 apples.

Example 4

medium
If \(y = kx\) and \(y = 35\) when \(x = 7\), find \(k\) and predict \(y\) when \(x = 12\).