1. Year-3
The standard deviation plus or minus 3 for 99.2% for year three will cover a standard deviation from to
To calculate the normal distribution we need the z value, mean and standard deviation. Placing the value into excel using the following formula z = (x - μ) / σ. z = z-score, x = raw score or observation to be standardized μ = mean of the population, σ = standard deviation of the population. For year one the mean is and the standard deviation of population is Using the standard deviation of 68% from the first year use a number in between and Let’s use and a number below the standard deviation 1000.
For z score will be approximately = ( )/ this means that the normal deviation is above of the standard deviation of 68%
For a sample of 1000 z score will be approximately = ( )/ The standard deviation of 68% of 1000 is below