Question

1)Given a sample mean is82, the sample size is 100and the population standard deviation is 20. Calculate the margin of error to 2 decimalsfor a 90% confidence level.

2)Given a sample mean is 82, the sample size is 100 and the population standard deviation is 20. Calculate the confidence interval for 90% confidence level. What is the lower limit value to 2 decimals?

3)Given a sample mean is 82, the sample size is 100 and the population standard deviation is 20. Calculate the confidence interval for 90% confidence level. What is the upper limit value to 2decimals?

4)Given a population standard deviation of 240, margin of error of 69 and a 95% confidence level, calculate the sample size rounded up to a whole number.

Example: For sample size calculation of 34.23, round up to 35

Answer 1

1)

Mean = 82

Sample size (n) = 100

Standard deviation (s) = 20

Confidence interval(in %) = 90

z @ 90% = 1.645

Since we know that

2)

Required confidence interval = (82.0-3.29, 82.0+3.29)

Required confidence interval = (78.71, 85.29)

Lower Limit: 78.71

3)

Required confidence interval = (82.0-3.29, 82.0+3.29)

Required confidence interval = (78.71, 85.29)

Upper Limit: 85.29

4)

z @ 95% = 1.96

E = 69

s = 240

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