let
P(h)= probability of selecting heart = 13/52= 1/4
similarly
P(s)= probability of selecting spade =1/4
P(c)= probability of selecting club =1/4
P(d)= probability of selecting diamond =1/4
a)
P(h or s)= P(h)+P(s)= 1/4+1/4=2/4=1/2=0.5
b)
P(h or s or c)=P(h)+P(s)+P(c)=1/4+1/4+1/4=3/4=0.75
c)
P(2 or a diamond)=n(2heart, 2spade,2club,13 diamonds)/total number of cards
=(1+1+1+13)/52=16/52=4/13=0.3
or we could solve it as follows:
P(2 or a diamond)=P(2)+P(diamond)-P(2diamond)=4/52 + 13/52 + 1/52 = (4+13-1)/52=16/52=0.3