Find the minimum sample size n needed to estimate u for the

Find the minimum sample size n needed to estimate u for the given values of c, s, and E. c=0.90, s=9.3, and E=1. Assume that a perliminary sample has at least 30 members. n=_ round up to the nearest whole number.

Compute Sample Size
n = (Z a/2 * S.D / ME ) ^2
Z/2 at 0.1% LOS is = 1.64 ( From Standard Normal Table )
Standard Deviation ( S.D) = 9.3
ME =1
n = ( 1.64*9.3/1) ^2
= (15.252/1 ) ^2
= 232.624 ~ 233