Question

If $z$ varies directly as $x$ and inversely as $y$. Find the percentage increase of $12\%$ in $x$ and a decrease of $20\%$ in $y$.

Answer 1

Given zronies directly $x$ and inversely as $4$

Hence $z=\left(x/4\right)$. Assuming proportionate constant $1x,$ is increased by $12\%$ and $y$ is decreased by $20\%$

$z=1.12x/0.8y$

$z=112x/80y$

Change in volume $nz$

$=(112\times 8/80y)-\left(x/y\right)$

$=32\times /80y$

Increase in $2^{\prime }s$ percentage

$=\left(32x/80y\right)÷\left(x/y\right)\times 100$

$=40\%$