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?
246,247,267,276,264,274


426,427,467,476,462,472


624,627,672,674,647,642


724,742,762,764,726,746


a) 4 in 6 + 4 in 6 + 4 in 6 + 6 in 6=18 in 24=3 in 4


b)reverse of a)=1 in 4


c)9 in18+0 in 6=9 in 24


d) 1 in 2


e) 18 in 24=3 in 4