A researcher wishes to estimate within 2 the time average am

A researcher wishes to estimate, within $2, the time average amount of postage a person spends each year. If she wishes to be 98% confident, how large a sample is necessary? The standard deviation is known to be $6.

Solution

Margin of error= 2

Std dev =6

Ztab = 2.34

n =(Ztab *std dev)/E

= 48.86~ 49.