The time taken to discharge a patient in a hospital depends on many factors such as insurance clearance, clearing bills not covered under insurance, etc. A hospital sets a target that the time to discharge a patient should be less than 120 minutes; any discharge taking more than 120 minutes is considered as unacceptable. Analysis of previous data has shown that the average time taken to discharge a patient is 150 minutes with a standard deviation of 20 minutes (assume normal distribution). Calculate the Sigma Score of the discharge process. If the calculated Sigma Score is negative, explain under what conditions the process will have negative Sigma Score.