Five (5) years ago a study of large businesses was conducted. It was found that the average revenue of the large businesses was R24 billion with a standard deviation of R6.8 billion. see if the average revenue has changed. You wish to construct a 95% confidence interval for the current average revenue of large businesses and need to decide how many businesses to include in your sample. What is the minimum sample size you should use if you want your estimate to be within R1.5 billion of the true average? You assume the standard deviation of the revenue has not changed.