In an Australian chocolate factory, a machine produces Chocolate Bar of nominal weight 25g. It is believed that the actual weights of chocolate bars follow a normal distribution with a mean of 24.5g and a standard deviation of 1.5g. Tammy loves chocolate and she brought a big pack of chocolate which contains 40 chocolate bars.
Find the probability that the weight of a randomly selected chocolate bar from the pack is between 23.5g and 25.5g.