Help with math?

A 3-digit numeral is formed by selecting digits at random from 2, 4, 6, 7 without repetition. find the probability that the number formed is:


a) even


b) odd


c) contains only even digits


d) is greater than 600


e) less than 700

Help with math?
a) 10/16


b)6/16


c)6/16


d)8/16


e)12/16