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25 votes
25 votes
3. (5 points) A 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?

User Puudeli
by
2.4k points

1 Answer

19 votes
19 votes

Answer:

9.304

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

User Wassim Dhif
by
2.8k points