A coins is tossed three times,where E:aleast two heads,F: atmost two heads. Find P(E/F)

Explanation

Here,S = {HHH,HHT,HTH,HTT,THH,THT,TTH,TTT}
E={HHT,HTH,THH,HHH}
(because at least two heads means two heads or three heads)
F = {TTT,THT,TTH,HTT,HHT,HTH,THH}
(because at the most two heads means zero head or one head or two heads) `rArr EnnF = {HHT,HTH,THH} therefore P (EnnF)=3/8 and P(F)=7/8`.
Thus,P(E/F)=`(P(EnnF))/(P(F))`=3/8/7/8=3/7