It Has Been Reported That the Average Time to Download $\left[ \begin{array} { l l } .648 & 1.152\end{array} \right]$

It has been reported that the average time to download the home page from a government website was 0.9 seconds.Suppose that the download times were normally distributed with a standard deviation of 0.3 seconds.If random samples of 36 download times are selected,80 percent of the sample means will be between what two values symmetrically distributed around the population mean?

A) $\left[ \begin{array} { l l } .648 & 1.152\end{array} \right]$
B) $\left[ \begin{array} { l l } .836 & .964\end{array} \right]$
C) $\left[ \begin{array} { l l } .514 & 1.280\end{array} \right]$
D) $\left[ \begin{array} { l l } .858 & .942\end{array} \right]$