Help Please! Three people are selected at random from six females and eight males. Find the probability of the following At most two are male.
How many people are there total?
Tell the total number of people.
In total there are 14 people. At most you want 2 men out of the 14 people. Therefore the probability is \[\frac{ 2 }{ 14 }\] and simplified is \[\frac{ 1 }{ 7 }\]. The probability of 2 men is \[\frac{ 1 }{ 7 }\]
You'll need the binomial distribution for this one. The probability of a male being selected is \(p=\cfrac{8}{14}=\cfrac{4}{7}\) and probability of female is \(\cfrac{3}{7}\). If \(X\) represents the number of males selected, then $$ \large{ P(X\le x)=\sum_0^x\binom{14}{x}\left(\cfrac{4}{7}\right)^x\left(\cfrac{3}{7}\right)^{(14-x)}\\ } $$ So then, $$ P(X\le2)=\sum_0^2\binom{14}{x}\left(\cfrac{4}{7}\right)^x\left(\cfrac{3}{7}\right)^{(14-x)}\\ =\binom{14}{0}\left(\cfrac{4}{7}\right)^0\left(\cfrac{3}{7}\right)^{(14-0)}+\\ \binom{14}{1}\left(\cfrac{4}{7}\right)^1\left(\cfrac{3}{7}\right)^{(14-1)}+\\ \binom{14}{2}\left(\cfrac{4}{7}\right)^2\left(\cfrac{3}{7}\right)^{(14-2)} $$ Does this make sense?
Female = 5 Male= 9 Total = 14 persons Selecting 3 persons out of 14 = nCr=14C3 =14!/(14-3)! 3! =14*13*12*11!/11! 3! =14*13*12/3*2*1 = 2186/6 =364 ways Selecting 1 male out of 9 = nCr=9C1=9 ways Selecting 2 males out of 9 = nCr=9C2=9!/(9-2)!2!=9!/7!2!=9*8*7!/7!2!=9*4=36 ways Selecting 3 male out of 9 = nCr=9C3=9 ways=9!/(9-3)!3!=9!/6!3!=9*8*7*6!/6!3!=9*8*7/3*2*1=504/6=84 ways Selecting 1 female out of 5 = nCr=5C1=5 ways Selecting 2 females out of 5 = nCr=5C2=5!/(5-2)!2!=5!/3!2!=5*4*3!/3!2!=20/2=10 ways P(At least one is male) = (Selecting 1 male 2 femal + selecting 2 male 1 female + selectiong 3 male 0 female) / selecting 3 out of 14 persons P(At least one is male) = [(9C1*5C2) + (9C2*5C1) + (9C3*5C0)] / 14C3 P(At least one is male) = [(9*10)+(36*5)+(84*1)] / 364 P(At least one is male) = [(90+180+84)] / 364 P(At least one is male) =354/364 P(At least one is male)=0.9725 P(At most two are male)= (Selecting 1 male 2 femal + selecting 2 male 1 female) / selecting 3 out of 14 persons P(At most two are male) = [(9C1*5C2) + (9C2*5C1)] /14C3 P(At most two are male)= [(9*10)+(36*5)] / 364 P(At most two are male) = (90+180) / 364 P(At most two are male) =270/364 P(At most two are male) =0.7417 Ohh my God.... Typing made me tired a lot.. Well, Hey Sweet @nm61101 Wondering If you are satisfied with this answer, Please close this Question. Thank You ! Keep in touch with Open Study.. Bye !
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