The 25th, 50th, 75th, and 100th percentiles for X are called its first, second, third, and fourth quartiles respectively.
(a) State the definition of the first quartile in terms of probabilities.
(b) Let X be binomial with n = 20 and p = .5. Find the first quartile for X.
(c) Let X be exponentially distributed with 13 = 1. Find the first quartile for X.