please solve B

Based on available information, lead time demand for PC thumb drives averages 46 units (normally distributed), with a standard deviation of 5 drives. Management wants an 85% service level. Refer to the standard normal table for z-values. a) What value of Z should be applied? b) How many drives should be carried as safety stock? units (round your response to the nearest whole number). \begin{tabular}{|c|c|} \hline Z & Pr(Z) \\ \hline 0.38 & 65 \\ 0.50 & 69 \\ 0.67 & 75 \\ 0.84 & 80 \\ 1.04 & 85 \\ 1.28 & 90 \\ 1.41 & 92 \\ 1.56 & 94 \\ 1.65 & 95 \\ 1.75 & 96 \\ 2.06 & 98 \\ 2.33 & 99 \\ \hline \end{tabular}