When 3 unbiased coins are tossed once, then possible outcomes are:
TTT, TTH, THT, HTT, THH, HTH, HHT, HHH
Total number of outcomes = 8
We know,
Probability of occurrence of an event = (Total number of favorable outcomes) / (Total number of outcomes)
(i) exactly 2 tails
Possible outcomes: TTH, THT, HTT
Total number of outcomes = 3
Therefore, the probability of getting exactly 2 tails = 3/8
(ii) exactly one tail
Possible outcomes: THH, HTH, HHT
Total number of outcomes = 3
Therefore, the probability of getting exactly one tail = 3/8
(iii) at most 2 tails
Possible outcomes: THH, HTH, HHT, TTH, THT, HTT, HHH
Total number of outcomes = 7
Therefore, the probability of getting at most 2 tails = 7/8
(iv) at least 2 tails
Possible outcomes: TTH, THT, HTT, TTT
Total number of outcomes = 4
Therefore, the probability of getting at least 2 tails = 4/8 = 1/2
(v) at most 2 tails or at least 2 heads
Possible outcomes: TTH, THT, HTT, THH, HTH, HHT, HHH
Total number of outcomes = 7
Therefore, the probability of getting at most 2 tails or at least 2 heads = 7/8
