Growth Rates

Sales for Hanebury Corporation's just$-$ended year were $$9$ million. Sales were $$4\mathrm{.}5$ million $5$ years earlier.

a$.$ At what rate did sales grow? Do not round intermediate calculations. Round your answer to two decimal places. $$

$\%$

b$.$ Suppose someone calculated the sales growth for Hanebury Corporation in part a as follows: "Sales doubled in $5$ years. This represents a growth of $100\%$ in $5$ years; dividing $100\%$ by $5$ results in an estimated growth rate of $20\%$ per year." Explain what is wrong with this calculation.