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

The student's question pertains to calculating the probability of selecting two individuals from a sorority consisting of full members and pledges. The calculation involves using combinatorial formulas to determine the likelihood of different types of selections.

Step-by-step explanation:

The student is asking about finding the probability of selecting two persons at random from a group consisting of full members and pledges in a sorority. With 38 members in total, 28 full members and 10 pledges, we need to calculate the probability of different pairs of members being selected. This is a combinatorial probability question.

In such problems, if there is no specific requirement about who needs to be picked (like how many full members or pledges), the total number of ways to select two members from the group without regard to order is calculated using the combination formula C(n, k) = n! / [k!(n-k)!], where 'n' is the total number of items, and 'k' is the number of items to choose.

For instance, the probability of selecting two full members can be calculated by finding the number of ways to choose two full members from the 28 available, divided by the number of ways to choose any two members from the entire group of 38.

Answer 2

(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.