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?
Answers
━━━━━━━━━━━━━━━━━━━━━━━━━
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?
━━━━━━━━━━━━━━━━━━━━━━━━━
➡️Since either coin can turn up Head (H) or Tail (T), are the possible outcomes.
➡️But, now three coins are tossed once so the possible sample space contains,
➡️S = {HHH, HHT, HTH, THH, HTT, THT, TTH, TTH}
➡️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
➡️Therefore, A and C are mutually exclusive.
➡️A ∩ C = (HHH) ∩ (TTT)
➡️= φ
➡️There, A and C are mutually exclusive.
➡️A ∩ D = (HHH) ∩ (HHH, HHT, HTH, HTT)
➡️= (HHH)
➡️A ∩ D ≠ φ
➡️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)
➡️B ∩ D ≠ 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
➡️If an event has only one sample point of a sample space, it is called a simple (or elementary) event.
➡️A = (HHH)
➡️C = (TTT)
➡️Both A & C have only one element,
➡️so they are simple events.
✴➡️(iii) Compound events
➡️If an event has more than one sample point, it is called a Compound event
➡️B= (HHT, HTH, THH)
➡️D= (HHH, HHT, HTH, HTT)
➡️Both B & D have more than one element,
➡️So, they are compound events.
━━━━━━━━━━━━━━━━━━━━━━━━━
Answer:
➡️Since either coin can turn up Head (H) or Tail (T), are the possible outcomes.
➡️But, now three coins are tossed once so the possible sample space contains,
➡️S = {HHH, HHT, HTH, THH, HTT, THT, TTH, TTH}
➡️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✔
➡️Therefore, A and C are mutually exclusive.
➡️A ∩ C = (HHH) ∩ (TTT)
➡️= φ✔
➡️There, A and C are mutually exclusive.
➡️A ∩ D = (HHH) ∩ (HHH, HHT, HTH, HTT)
➡️= (HHH)✔
➡️A ∩ D ≠ φ
➡️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)✔
➡️B ∩ D ≠ 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
➡️If an event has only one sample point of a sample space, it is called a simple (or elementary) event.
➡️A = (HHH)✔
➡️C = (TTT)✔
➡️Both A & C have only one element,
➡️so they are simple events.
✴➡️(iii) Compound events
➡️If an event has more than one sample point, it is called a Compound event
➡️B= (HHT, HTH, THH)✔
➡️D= (HHH, HHT, HTH, HTT)✔
➡️Both B & D have more than one element,
➡️So, they are compound events.
Step-by-step explanation: