Suppose a random variable is . To determine the pth percentile of , we first need to find the pth percentile of To this end, the value ofat the pth percentile, denoted has 100 p% of the area under below it, that is, satisfies the equation
For instance, to find the 80th percentile of the distribution, let us work with the equation
(Fig. 6.27a). Then, since 0.80 = 0.50 + 0.30, let us find 0.30 ...