Question 366909
Without the help of further information we assume that scores on aptitude tests are normally distributed.  Since the normal distribution is a CONTINUOUS distribution, P(X = 100) = 0.  We can only talk about the CUMULATIVE DISTRIBUTION for a continuous distribution.  Thus we can only talk about {{{P(X>=100)}}} or 
{{{P(X<=100)}}}, which in either case is equal to 0.50.