The Amount Filled by a Certain Bottling Machine,X,is Approximately Normally

Multiple Choice

The amount filled by a certain bottling machine,X,is approximately normally distributed with unknown mean,μ,and standard deviation,σ =1.What is the minimum sample size,n,so that there is a probability of (at least) 0.9 that the sample mean will be within 0.2 ounces of the population mean?

A) 16
B) 28
C) 54
D) 68
E) 125