The length оf time, in hоurs, it tаkes аn "оver 40" group of people to plаy one soccer match is normally distributed with a mean of two hours and a standard deviation of 0.5 hours. A sample of size n = 50 is drawn randomly from the population. Find the probability that the sample mean is between 1.8 hours and 2.3 hours (round your result to 4 decimal places).