Question: Q4) The effect of Oat Bran was tested on subjects to ascertain the reduction of cholesterol levels. A 95% confidence interval for the mean \(\mu \) was on obtained and this had a margin of error of 0.2753 mmol/L. How large a study is needed to reduce the margin of error to 0.2 with 95% confidence? Explain why you need to use the correction factor to calculate this new sample size.