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Inverse proportion

Two quantities are proportional when one is a constant times the other, with no starting value. If you double one, you double the other. They are inversely proportional when the product is constant. If you double one, you halve the other. Work with more people is a common example: the number of worker-days is the same, so more workers take fewer days. You find the product first, and then divide.

y=kxy = kxproportional
x⋅y=kx \cdot y = kinversely proportional

Symbols

kkthe constant

Example

4 workers take 6 days. The worker-days are 4⋅6=244 \cdot 6 = 24.

8 workers take 24/8=324/8 = 3 days.

Inverse proportion: the product is constant. Proportion: the ratio is constant.
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