A football team consists of 19 each freshmen and sophomores , 15 juniors , and 13 seniors . Four players are selected at random to serve as captains . Find the probability of the following . Enter your answers as fractions or as decimals rounded to 4 decimal places . ( a ) All 4 are seniors. ( b ) There is 1 each : freshman, sophomore , junior , and senior. ( c ) There are 2 sophomores and 2 freshmen. ( d ) At least 1 of the students is a senior..