Given the following comulative propability distribution:

0 if x less than zero

x/2 if x between 0 and 1

1-(1/(2x)^2) if x greater than one.

what's the probability P(X=1)? isn't it zero since a continuous variable don't have probability in a single point? cause my book says it's 1/4 and I'm confused about it... probably I'm mistaken...don't know