R.PHYPER(x,r,b,n,lower_tail,log_p)
x: observation
r: the number of red balls
b: the number of black balls
n: the number of balls drawn
lower_tail: if true (the default), the lower tail of the distribution is considered
log_p: if true, log of the probability is used
This function returns the cumulative distribution function of the hypergeometric distribution.