Question

The variable Z is directly proportional to X. When X is 3, Z has the value 54.
What is the value of Z when X = 12

Answer 1

\[given\ Z\ is\ directly\ proportionalto\ X\\ \implies\ Z \alpha\ X\\ \implies\ Z=kX\ [where\ k\ is\ a\ constant]\\now\ when\ X=3, Z=54\\ i.e.\ 54=k\ \times3\\ \therefore\ k=54\div3\\k= 18\\NOW\ when\ X=12,\ we\ have\ Z=kX\\ \therefore\ Z= 18\times 12 \\ \therefore\ Z=218\]