A Population Has a Standard Deviation $\sigma = 19.8$ How Large a Sample Must Be Drawn So That

Multiple Choice

A population has a standard deviation $\sigma = 19.8$ . How large a sample must be drawn so that a $99 \%$ confidence interval for $\mu$ will have a margin of error equal to $4.7 ?$

A) 215
B) 118
C) 7
D) 11