Probability of one dealt is $\frac{Total possible full house pairs}{Total possible pairs}$
Total Possible full house pair = 13*12*24=3744
For 3 of an kind we have to choose 2 different denomination of card i.e (3,4)= 3,3,3,4,4 but (4,3)=4,4,4,3,3 thus order matters so this can be done by 13P2 ways =13*12
form 4 cards of same denomination we can choose 3 in 4C3 ways =4
form 4 cards of same denomination we can choose 2 in 4C2 ways =6
Total possible full house is 13*12*4*6=3744
Finding total possible combination is easy we have 52 cards and 5 positions thus52C5 ways
P(Full House)=$\frac{3744}{^{52}C_{5}}$