Category: Permutation and Combination

Question Number 182695 by cortano1 last updated on 13/Dec/22 $$\mathrm{If}\mathrm{two}\mathrm{events}\mathrm{A}\mathrm{and}\mathrm{B}\mathrm{are}\mathrm{such}$$$$\mathrm{that}\mathrm{P}\left({\mathrm{A}}^{\mathrm{c}}\right)=0.3;\mathrm{P}\left(\mathrm{B}\right)=0.4\mathrm{and}$$$$\mathrm{P}(\mathrm{A}\cap {\mathrm{B}}^{\mathrm{c}})=0.5\mathrm{then}\mathrm{P}\left(\frac{\mathrm{B}}{\mathrm{A}\cup {\mathrm{B}}^{\mathrm{c}}}\right)=?$$$$\left(\mathrm{A}\right)0.20\left(\mathrm{B}\right)0.25\left(\mathrm{C}\right)0.30\left(\mathrm{D}\right)0.35$$$$$$ Commented by…

Question Number 116881 by bemath last updated on 07/Oct/20 $$\mathrm{Find}\mathrm{the}\mathrm{number}\mathrm{m}\mathrm{of}\mathrm{non}\mathrm{negative}$$$$\mathrm{integer}\mathrm{solution}\mathrm{of}\mathrm{x}+\mathrm{y}+\mathrm{z}=18$$$$$$ Answered by john santu last updated on 07/Oct/20 $${we}\:{can}\:{view}\:{each}\:{solution}\:,{say}\:{x}=\mathrm{3},\:{y}=\mathrm{7}\:,{z}=\mathrm{8}…

Question Number 51286 by aseerimad last updated on 25/Dec/18 Answered by mr W last updated on 26/Dec/18 $$Type1:$$$$NumberofwordsstartingwithD:$$$$=\frac{7!}{2!}=2520$$$$ \…

Question Number 181971 by Acem last updated on 03/Dec/22 $$Howmanywordscanbeformedfromdifferent$$$$lettersofthe“Youransweris{wrong}^{″}withnot$$$$repeating?Sothatthey{shouldn}^{\prime }tstartwith{}^{\prime }{o}^{\prime }$$$$neither{}^{\prime }{w}^{\prime }and{shouldn}^{\prime }tendwith{}^{\prime }{w}^{\prime },and$$$$should{be}^{\prime }{r}^{\prime }\mathrm{\&}{}^{\prime }{s}^{\prime }adjacents.$$$$$$$$\cancel{Oya}\dots n,\cancel{Wen}\dots y,Iog\dots \cancel{w},You\cancel{rw}\cancel{s}\dots e:areinvalid$$$$\:{Enrsow}…{g}\::\:{is}\:{valid} \…

Question Number 116397 by john santu last updated on 03/Oct/20 $$Thenumber1,2,3,4,\dots ,7arerandomly$$$$dividedintotwonon-emptysubsets.$$$$Theprobabilitythatthesumofthe$$$$numbersinthetwosubsetsbeing$$$$equalis\frac{r}{s}expressedinthelowest$$$$term.Findr+s?$$ Answered by…