Three coins are tossed once. Find the probability of getting (i) 3 heads (ii) 2 heads
Three coins are tossed once. Find the probability of getting (i) 3 heads (ii) 2 heads

When a coin is tossed the possible outcomes are either a Head \left( H \right) or Tail \left( T \right).

Here, coin is tossed three times then the sample space contains,

S{\text{ }} = {\text{ }}\left\{ {HHH,{\text{ }}HHT,{\text{ }}HTH,{\text{ }}THH,{\text{ }}TTH,{\text{ }}HTT,{\text{ }}TTT,{\text{ }}THT} \right\}

And n\left( S \right){\text{ }} = {\text{ }}8.

(i) 3 heads

Suppose A be the event of getting 3 heads

Then, n\left( A \right) = {\text{ }}1

P(A) = \frac{{n(A)}}{{n(S)}}

Therefore, P(A) = \frac{1}{8}.

(ii) 2 heads

Suppose B be the event of getting 2 heads

Then, n{\text{ }}\left( A \right){\text{ }} = {\text{ }}3

P(B) = \frac{{n(B)}}{{n(S)}}

Therefore, P(B) = \frac{3}{8}.