Over the last year, customers who have phoned their cable company for technical support have had to wait for a cus average of $28$ minutes, with a standard deviation of $5\mathrm{.}5$ minutes. Company records have shown wait times to be nor that a person phones the cable company and waits more than $30$ minutes for service?

Select one:

a$.5541$

b$.6212$

c$.\mathrm{.}0382$

d$.3581$