The 160 students at EBA are all registered with the university dentist. Of the 7

Question

The 160 students at EBA are all registered with the university dentist. Of the 75 girls only 25 of them have seen the dentist in the past year for treatment, the others have not. 34 of the boys received treatment and the rest have not. Each student has a separate record card. (a) A record card is selected at random. Let A represent the event that the student referred to on the card has received treatment in the past year, and the event B represent that the student referred to is a boy. Find P(B), P(A and B), P(A and B), P(-A and~B), P(-A or~B) and P(BA).

Explanation / Answer

here number of boys =160-75 =85

therefore P(B) =75/160

P(A and B) =34/160

P(A and ~B) =25/160

P(~A and ~B) =(75-25)/160 =50/160

P(~A or ~B)=(160-34)/160 =126/160

P(B|A) =P(A and B)/P(A) =(34/160)/((34+25)/160)=34/59

b)probability =(59/160)*(58/159)*(57/158)=0.0485

c)probability =3*(59/160)*(101/159)*(100/158) =0.4448

d) probability =3*(25/160)*(34/159)*(50/158)=0.0317

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