The curve, which is often a good model for a company's variable costs, is expressed as y$=$

$\backslash$beta $\_(1)$x$+\backslash$beta $\_(2)$x$^(2)+\backslash$beta $\_(3)$x$^(3),$ where x represents the sales level. $($There are no constant term since fixed

costs are not included.$)$

a$-($x$\_(1),$y$\_(1))$dots$($x$\_($n$),$y$\_($n$)).$

b$-4\mathrm{.}27,2\mathrm{.}496\mathrm{.}12,4\mathrm{.}328\mathrm{.}09,6\mathrm{.}4510\mathrm{.}30,8\mathrm{.}2116\mathrm{.}58,14\mathrm{.}33$