Direct Variation Math Example 2
Follow the full solution, then compare it with the other examples linked below.
Example 2
mediumThe cost of fabric varies directly with length. 5 meters costs \$35. How much do 8 meters cost? Set up a proportion.
Solution
- 1 Direct variation: \(C = kL\).
- 2 Find \(k\): \(k = 35/5 = 7\) (\$7 per meter).
- 3 Equation: \(C = 7L\).
- 4 For \(L=8\): \(C = 7 \times 8 = 56\).
- 5 8 meters costs \$56.
Answer
\$56
Direct variation gives the unit rate: \7/meter. Multiply by 8 meters: \(7 \times 8 = \56\).
About Direct Variation
A proportional relationship that always passes through the origin โ when one quantity doubles, so does the other.
Learn more about Direct Variation โMore Direct Variation Examples
Example 1 easy
(y) varies directly with (x), and (y = 18) when (x = 3). Find the constant (k) and write the direct
Example 3 easyIf (y = kx) and (y = 24) when (x = 4), find (y) when (x = 7).
Example 4 mediumA machine produces 150 units in 5 hours. Assuming direct variation, how many units in 9 hours?