The Sample Space S,S, associated with the Experiment of
tossing a coin thrice is,
S={(H,H,H),(H,H,T),(H,T,H),(H,T,T),(T,H,H),(T,H,T),(T,T,H),(T,T,T)}.S={(H,H,H),(H,H,T),(H,T,H),(H,T,T),(T,H,H),(T,H,T),(T,T,H),(T,T,T)}.
:. n(S)=8.
E=the Event getting at least one Head
=the Event getting no. of Heads 1, or, 2, or 3
:. E={(H,H,H),(H,H,T),(H,T,H),(H,T,T),(T,H,H),(T,H,T),(T,T,H)}.
:. n(E)=7.
:. P(E)=(n(E))/(n(S))=7/8.
As an Aliter, we note that,
E'=the Complementary Event of the Event E
=the Event getting not a single Head at all
:. E'={(T,T,T)} rArr P(E')=1/8.
:. P(E)=1-P(E')=1-1/8=7/8.
Enjoy Maths.!
