Finding the sample size of 95% level confidence.
A consumer group would like to estimate the average amount of PG&E bill for the month of March for single family homes in the San Francisco Bay Area. Based on studies conducted in other similar climate cities, the standard deviation is assumed to be $25. The group would like to estimate the average March bill to be with 5 of the population average with 95% level confidence.
Find the sample size needed.
a) 166
b) 97
c) 158