Joint and combined variation worksheet
Joint variation multiplies: z = kxy. Combined variation mixes direct and inverse: z = kx over y. Either way the method is the same as direct variation, use the first set of values to find k, then use k with the second set.
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Sigma Prep · sigmaprep.io/worksheets Name Joint and Combined Variation Date Period Answer each question.
Free math worksheets at sigmaprep.io/worksheets© 2026 Sigma Prep |
Sigma Prep · sigmaprep.io/worksheets Name Joint and Combined VariationAnswer keyVersion 1 Date Period Answer each question.
Free math worksheets at sigmaprep.io/worksheets© 2026 Sigma Prep |
How to do these
varies jointly with and , and when , . Find when and
- z = kxy, so 24 = 6k and k = 4.
- z = 4 times 4 times 5.
The answer is .
Where students go wrong
Adding where the variation multiplies. "Varies jointly with x and y" is kxy, never k(x + y).
Also called joint variation, combined variation or constant of variation.
What you can put on this worksheet
- Direct variation
- varies directly as . When , . Find when . →
- Inverse variation
- Suppose is inversely proportional to , and when . Find when . →
- Joint variation
- For boxes of one height, the volume varies jointly with the length and the width , and when and . Find when and . →
- Combined variation
- The pressure of a gas varies directly with its temperature and inversely with its volume . If when and , what is when and ? →
- Direct, inverse or neither
- Does vary directly with , inversely with , or neither? → Inverse,
- With a square or a cube
- If varies directly with the square of and when , find when . →
- Direct, inverse, or neither?
- Does vary directly with , inversely with , or neither? → Direct,
- Rearranged equations, k in a denominator
- Direct, inverse or neither? If it varies, find : → Inverse,