Answer:
The increase in cost is [tex]C _{(900 - 450 )} =[/tex] $ 213750
Step-by-step explanation:
From the question we are told that
The marginal cost function is [tex]C \ '(x) = 700 -\frac{x}{3}[/tex] where [tex]0 \le x \le 900[/tex]
Since [tex]C \ '(x)[/tex] is in dollars it means that [tex]C(x)[/tex] is the cost price and x is given as the number of bikes now to obtain [tex]C(x)[/tex] for the given increase of the number of bikes we integrate [tex]C\ '(x)[/tex] within the increase limit
This can be evaluated as
[tex]\int\limits^{900}_{450} {C \ '(x)} \, dx = \int\limits^{900}_{450} {700 - \frac{x}{3} } \, dx[/tex]
[tex]C(x) = [ {700x - \frac{x^2}{6} }] \left 900} \atop {450}} \right.[/tex]
[tex]C _{(900 - 450 )} = [700(900) - \frac{900^2}{6} ] - [700(450) - \frac{450^2}{6} ][/tex]
[tex]C _{(900 - 450 )} = 495000- 281250[/tex]
[tex]C _{(900 - 450 )} =[/tex] $ 213750