A continuous random variable X that can assume values between x=2 and x=4 has a density function given by
Show that P (2<x<4) =1
Integrate f(x) from 2 to 4 and you get an answer of 6.25, not 1. Therefore, it is not a correct pdf. However, if you meant , it does satisfy having an integral of one. To find the probability that x is less than 3.5, integrate the pdf from 2 to 3.5.