Three coins are tossed once. Let A denote the event ‘three heads show”, B denote the event “two heads and one tail show”, C denote the event” three tails show and D denote the event ‘a head shows on the first coin”. Which events are

(i) mutually exclusive?


(ii) simple?


(iii) Compound?

Here, three coins are tossed once so the possible outcomes or sample space (S) consist of

S=


Now,


A: ‘three heads’


A= (HHH)


B: “two heads and one tail”


B= (HHT, THH, HTH)


C: ‘three tails’


C= (TTT)


D: a head shows on the first coin


D= (HHH, HHT, HTH, HTT)


(i) Mutually exclusive


A B = (HHH) (HHT, THH, HTH)


= ϕ


Since there is no common element between A&B,


they are mutually exclusive


A C = (HHH) (TTT) = ϕ


Since here is no common element,


So, A and C are mutually exclusive.


A D = (HHH) (HHH, HHT, HTH, HTT)


= (HHH) ≠ ϕ


Since there is a common element in A and D


So they are not mutually exclusive


B C = (HHT, HTH, THH) (TTT) = ϕ


Since there is no common element in B & C, so they are mutually exclusive.


B D = (HHT, THH, HTH) (HHH, HHT, HTH, HTT)


= (HHT, HTH) ≠ ϕ


Since there are common elements in B & D,


so, they not mutually exclusive.


C D = (TTT) (HHH, HHT, HTH, HTT) = ϕ


Since there is no common element in C & D,


So they are not mutually exclusive.


(ii) Simple event


An event is said to be simple if it has only one sample point in its sample space.


Here A = (HHH)


C = (TTT)


Both A & C have only one element,


so they are simple events.


(iii) Compound events


Is an event has more than one sample point of a sample space , it is called as compound event.


Here B= (HHT, HTH, THH)


D= (HHH, HHT, HTH, HTT)


Both B & D have more than one element,


So, they are compound events.


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