margin of error is important in determining the probability as it gives realistic data for the distribution. The formula to be followed for margin of error is m% = z* sqrt (p*(1-p))/n where p is the % positive outcome, n is the sample size and z* is a constant dependent to % confidence level. Substituting, m% = z* (0.03). Level of confidence is not given but assuming at95% CF, m% = 6%