Answer:
9.304
Step-by-step explanation:
company wishes to estimate the mean monthly electric bill. If the standard
deviation is $400, how large a sample is required to estimate the mean electric bill to within $100
with 98% confidence?
Sample size, n = (Zcritical * σ) ÷ ME
σ = standard deviation ;
ME ≥ margin of error
α = 98% ; At 98% confidence level ;Zcritical = 2.326
n ≥ (2.326 * 400) / 100
n ≥ 930.4 / 100
n ≥ 9.304
n = 10
