A game consists of tossing a one-rupee coin three times, and nothing its outcome each time. Find the probability of getting (i) three heads, (ii) at least 2 tails.
When a coin is tossed three times, all possible outcomes are
HHH, HHT, HTH, THH, HTT, THT, TTH and TTT.
The total number of elementary outcomes = 8.
(i) Let E be the event of getting three heads
The favourable outcome with three heads is HHH.
The number of outcomes with three heads = 1.
Therefore, P (getting three heads) = P (E) = 1/8
(ii) let E be the event of getting at least two tails
Favourable Outcomes with at least two tails are TTH, THT, HTT and TTT.
Note: - at least two tails means there could be two or more than two tail so we will not consider the outcome with all head or less than two tales.
The number of favourable outcomes = 4.
∴ P (getting at least two tails) = P (E) = 4/8 = 1/2