Question

A sorority has 38 members, 28 of whom are full members and 10 are pledges. Two persons are selected at random from the membership list of the sorority. Find the requested probabilities. (Enter the probabilities as fractions.)

Answer 1

Answer:

(a) 185/703

(b) 518/703

(c) 45/703

(d) 140/703

(e) 140/703

(f) 378/703

(g) 185/703

Step-by-step explanation:

Let the event of pledge member be P and event of full member be F

(a)If the first is a pledge, then the second is either a pledge or a member.

required Probabability = [P n (PUF)]

= Pr(PnP) U Pr (PnF)

= 10/38 × 9/37 + 10/38 × 28/38

= 90/1406 + 289/1406 = 370/1406

= 185/703

(b) if the person selected is not a pledge then the person is a full member and the second is either a full member or pledge

The required probability = Fn(FUP) =Pr (FnP) U Pr(FnF)

= 28/38 × 10/37 + 28/38 × 27/37

= 280/1406 + 756/140 = 1036/1406

= 518/703

(c) probability required= Pr(P/P) = Pr(PnP) = 10/38 × 9/37

= 90/1406

= 45/703

(d) Probability required = Pr(F/P)

= Pr(P) nPr(F) = 10/38 × 28/37

= 280/1406

= 140/703

(e) Probability required = Pr(P/F)

= Pr(F) n Pr(P)

= 28/38 × 10/37 =280/1406

=140/704

(f) Probability required = Pr (FnF)

= Pr(F) n Pr(F)

= 28/38 × 27/37= 756/1406

= 378/703

(g) it is the either the first person is a pledge member or a full member

Probability required = Pr[(PnP) U (FnP)]

= Pr(PnP) + Pr(FnP)

= 10/38 × 9/37 + 28/38 × 10/37

= 90/1406 + 280/1406

= 370/1406

= 185/703

(h) see attachment.