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Question
Three unbiased coins are tossed. What is the probability of getting (a ) at least two head (b) at most two heads (c)two heads
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Solution
When 3 unbaised coins are tossed, the total number of events = 8
They are {HHH, HHT, HTH, THH, TTH, THT, HTT, TTT}
(1) Number of favourable events (getting at least two heads) = 4
Probability of getting at least two heads = 4/8 = 1/2
(2) At most two heads
That is no head or one head or 2 heads
Probability of getting at most two heads = 7/8
3) Two head = 3
(HHT,HTH,THH)
Probability of getting no head = 3/8.
They are {HHH, HHT, HTH, THH, TTH, THT, HTT, TTT}
(1) Number of favourable events (getting at least two heads) = 4
Probability of getting at least two heads = 4/8 = 1/2
(2) At most two heads
That is no head or one head or 2 heads
Probability of getting at most two heads = 7/8
3) Two head = 3
(HHT,HTH,THH)
Probability of getting no head = 3/8.
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