

InterviewSolution
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Three coins are tossed. Describe(i) two events A and B which are mutually exclusive.(ii) three events A, B and C which are mutually exclusive and exhaustive.(iii) two events A and B which are not mutually exclusive.(iv) two events A and B which are mutually exclusive but not exhaustive. |
Answer» Given: Three coins are tossed. When three coins are tossed, then the sample space is S = {HHH, HHT, HTH, HTT, THH, THT, TTH, TTT} Now, the subparts are: (i) The two events which are mutually exclusive are when, A: getting no tails B: getting no heads Then, A = {HHH} and B = {TTT} So, the intersection of this set will be null. Or, the sets are disjoint. (ii) Three events which are mutually exclusive and exhaustive are: A: getting no heads B: getting exactly one head C: getting at least two head So, A = {TTT} B = {TTH, THT, HTT} and C = {HHH, HHT, HTH, THH} Since, A ⋃ B = B ⋂ C = C ⋂ A = Փ and A⋃ B⋃ C = S (iii) The two events that are not mutually exclusive are: A: getting three heads B: getting at least 2 heads So, A = {HHH} B = {HHH, HHT, HTH, THH} Hence, A ⋂ B = {HHH} = Փ (iv) The two events which are mutually exclusive but not exhaustive are: A: getting exactly one head B: getting exactly one tail So, A = {HTT, THT, TTH} and B = {HHT, HTH, THH} It is because A ⋂ B = Փ but A⋃ B ≠ S |
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