Question

If f(x) varies directly with x and f(x)= 90 when x=50, find the value of f(x) when x=10.Round you final answer to the nearest whole number. Show work

Answer 1

We know that f(x) varies directly with x, this means that the function can be written as:

$f(x)=kx$

we also know that when f(x)=90 then x=50, then we have:

$\begin{gathered} 90=50x \\ x=\frac{90}{50} \\ x=\frac{9}{5} \end{gathered}$

Hence the function is:

$f(x)=\frac{9}{5}x$

is x=10 then we have:

$f(10)=\frac{9}{5}(10)=18$

Therefore the value of f(x) is 18 when x=10