$5-11$ GROWTH RATES Sawyer Corporation's $2020$ sales were $$5$ million. Its $2015$ sales were $$2\mathrm{.}5$ million.

a$.$ At what rate have sales been growing?

b$.$ Suppose someone made this statement: "Sales doubled in $5$ years. This represents a growth of $100\%$ in $5$ years; so dividing $100\%$ by $5,$ we find the growth rate to be $20\%$ per year." Is the statement correct?