standard deviation $8\mathrm{.}3\%.$

a$.$ For what proportion of these corporations was the rate of return higher than $17\%?$

b$.$ For what proportion of these corporations was the rate of return negative?

c$.$ For what proportion of these corporations was the rate of return between $10\%$ and $20\%?$

Click the icon to view the standard normal table of the cumulative distribution function.

a$.$ The proportion of corporations whose rate of return was higher than $17\%$ is

$($Round to four decimal places as needed.$)$