Question
Sat May 21, 2011 By: Joseph George

two different coins are tossed simultaneously. find the probalibity of getting: 1) two tails 2) one tail 3)no tail 4)atleast one tail 5)atmost one tail

Expert Reply
Sun May 22, 2011
If two unbiased coins are tossed simultaneously, following outcomes are obtained:
TT, TH, HT, HH
Total number of elementary events = 4
 
1) Two tails are obtained if the elemnetary event TT occur.
Favourable number of elementary events = 1
Hence required probability = 1/4.
 
2)One tail is obtained if any one of the following elementary events occur:
HT, TH
Favourable number of elementary events = 2
Hence required probability = 2/4 = 1/2
 
3)No tail is obtained if the elementary event HH occurs
Favourable number of elementary events = 1
Hence required probability = 1/4.
 
4)At least one tail is obtained if any of the following elementary events occur:
TT, TH, HT
Favourable number of elementary events = 3
Hence required probability = 3/4.
 
5)If one of the elementary events HT, TH, TT occurs , we say that at most one tail is obtained.
Favourable number of elementary events = 3
Hence required probability = 3/4.
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