Spar, in Vanderbijlpark, decided to record the daily average amount of money spent by its customers during February, to investigate the proposal of introducing a rewards program for their loyal customrers. The records indicate that the amount spent by the customers can be modeled by a distribution with mean R65 and standard deviation R6. If a random sample of 60 customers are selected from the records, what is the probability that the sample mean will lie between R63 and R66?