Example $2$: Norris Inc. finds that it sells $N(x)$ thousand units of a product after spending $x$ thousands of dollars on advertising, where

$N(x)=2500-1500e^{-0\mathrm{.}05x}$

Use $N^{\text{'}}(x)$ to estimate how many more units Norris will sell by increasing its advertising expenditure from $$100,000$ to $$101,000.$