A coin is tossed three times. Find the probability of getting at most 2 heads

Answer

A coin is tossed three times. `S={HHH,HT T, HTH,THH,T TH, THT,HHT,T T T}`
`|S|=8`
Let B be the event of getting almost 2 heads
`thereforeB={HT T,HTH,THH,T TH,THT, HHT, T T T}`
`implies |B|=7`
`therefore P(B)=|B|/|S|=7/8`