# Calculating the probability of exceeding a given return

I have calculated the return of an investment with cost and benefit data as 80% with a 4.6% coefficient of variation. However, I need to carry the analysis further by calculation the probability of exceeding a 20% return. I did these calculations using data from a survey. A multi-stage sample method was used to draw 300 respondents, therefore, I assume the distribution will approximate a normal one. Can anyone help me with information about how to go about it urgently? Thanks

• Welcome to CV! Can you provide more details about your problem that makes it easy for a person not familiar with the field to understand the underlying problem? Are the returns expected to follow a normal distribution? – rightskewed Jan 23 at 0:33
• If these are financial returns, then there should be very few cases that the returns will be normally distributed. That assumption is far from a safe one. If you need a quick answer, what percentage of your actual returns exceeded 20% in your survey? It would help if you could provide a survey question or two in order to see what your data looked like, or a formula that describes what you asked for. – Dave Harris Jan 23 at 22:55