WAEC 2020 · Paper 1 · Q16

Variation

Given that $x$ is directly proportional to $y$ and inversely proportional to $z$ , and $x = 15$ when $y = 10$ and $z = 4$ , find the equation connecting $x$ , $y$ and $z$ .

Worked solution (try it first)

Directly as $y$ , inversely as $z$ : $x = \dfrac{ky}{z}$ .
Put in $x = 15$ , $y = 10$ , $z = 4$ : $15 = \dfrac{10k}{4}$ , so $k = \dfrac{60}{10} = 6$ .
So $x = \dfrac{6y}{z}$ , option A.

Report a problem with this question