Areas under the curve correspond to the probability of a
value falling into the relevant interval.
For instance, 50% of the time, a variable with DF
of 5 will be in the range 0-4.35. 99% of the time the value
will fall under 15.09, meaning that there is only a 1% chance of
getting a random variable with 5 degrees of freedom
above this level.
variable with DF
of 5 will be in the range 0-4.35. 99% of the time the value
will fall under 15.09, meaning that there is only a 1% chance of
getting a random 
