A team of medical students doing their internship have to assist during surgeries as a city hospital. The probabilities of surgeries rated as very complex, complex, routine simple or very simple respectively, 0.15, 0.20, 0.31, 0.26 and 0.08. Find the probabilities that a particular surgery will be rated.
(i) Complex or very complex.
(ii) Neither very complex nor very simple.
(iii) Routine or complex.
(iv) Routine or simple.
Let Let E1,E2,E3,E4 and E5 be the event that surgeries are rated as very complex, complex, routine, simple or very simple, respectively then according to the given information:
P(E1)=0.15,P(E2)=0.2,P(E3)=0.31,P(E4)=0.26,P(E5)=0.08
(i) To find the probabilities that a particular surgery will be rated complex or very complex:
⇒P(E1∪E2)=P(E1)+P(E2)−P(E1∩E2)
=0.15+0.2−0
∴P(E1∪E2)=0.35
(ii) To find the probabilities that a particular surgery will be rated neither very complex nor very simple:
⇒P(E′1∩E′5)=P(E1∪E5)′=1−P(E1∪E5)
=1−[P(E1)+P(E5)]
=1−[0.15+0.08]
=1−0.23
∴P(E′1∩E′5)=0.77
(iii) To find the probabilities that a particular surgery will be rated Routine or complex:
⇒P(E3∪E2)=P(E3)+P(E2)−P(E3∩E2)
=0.31+0.2−0
∴P(E3∪E2)=0.51.
(iv) To find the probabilities that a particular surgery will be rated routine or simple:
⇒P(E3∪E4)=P(E3)+P(E4)−P(E3∩E4)
=0.31+0.26−0
∴P(E3∪E2)=0.57.