Answer
The cost function is $C\left( x \right)=100,000+100x$ and $C\left( 90 \right)=\$109,000$, which means that it costs $\$109,000$ to produce 90 bicycles.
Work Step by Step
Since the number of bicycles produced is represented by x, the total variable cost is given as,
$100\times x=\$100x$
Now it is given that total cost is the sum of a fixed cost and a total variable cost, that is
$\begin{align}
& C\left( x \right)=\text{fixed cost+total variable cost} \\
& =100,000+100x
\end{align}$
Thus, the cost function is given as,
$C\left( x \right)=100,000+100x$
Substitute the value of $x=90$ in the cost function to determine $C\left( 90 \right)$ ,
$\begin{align}
& C\left( 90 \right)=100,000+100\times 90 \\
& =100,000+9000 \\
& =\$109,000\end{align}$
This means that it costs $\$109,000$ to produce 90 bicycles.
