Category: Permutation and Combination

Question Number 133995 by mr W last updated on 26/Feb/21 $$inhowmanywayscannmenand$$$$nwomenbearrangedinarowsuch$$$$thatmenandwomenalternate?$$ Commented by benjo_mathlover last updated on 26/Feb/21 $$=\:\mathrm{2}×\mathrm{n}!×\mathrm{n}!\:=\:\mathrm{2}×\left(\mathrm{n}!\right)^{\mathrm{2}}…

Question Number 133658 by liberty last updated on 23/Feb/21 Commented by mr W last updated on 23/Feb/21 $$igetheadachewhenreadingsuch$$$$colorfultext,nottomentiontofind$$$$thecorrectsolution:)$$ Commented…

Question Number 133316 by bramlexs22 last updated on 21/Feb/21 $$\mathrm{How}\mathrm{many}6-\mathrm{letter}\mathrm{words}\mathrm{in}$$$$\mathrm{which}\mathrm{at}\mathrm{least}\mathrm{one}\mathrm{letter}\mathrm{appears}$$$$\mathrm{more}\mathrm{than}\mathrm{once},\mathrm{can}\mathrm{be}\mathrm{made}\mathrm{from}$$$$\mathrm{the}\mathrm{letters}\mathrm{in}\mathrm{the}\mathrm{word}\mathrm{FLIGHT}$$$$$$ Commented by mr W last…

Question Number 67454 by Aditya789 last updated on 27/Aug/19 Commented by mathmax by abdo last updated on 27/Aug/19 $${here}\:{C}_{{r}} \:{mean}\:{C}_{{n}} ^{{r}} \:\:\:\:\:\:{we}\:{have}\:\:\sum_{{r}=\mathrm{0}} ^{{n}} \:{C}_{{n}} ^{{r}}…

Question Number 132854 by EDWIN88 last updated on 17/Feb/21 $$\mathrm{It}\mathrm{is}\mathrm{required}\mathrm{to}\mathrm{seat}5\mathrm{men}\mathrm{and}4\mathrm{women}$$$$\mathrm{in}\mathrm{a}\mathrm{row}\mathrm{so}\mathrm{that}\mathrm{the}\mathrm{women}\mathrm{occupy}\mathrm{the}\mathrm{even}$$$$\mathrm{place}.\mathrm{How}\mathrm{many}\mathrm{such}\mathrm{arrangements}\mathrm{are}$$$$\mathrm{possible}?$$ Answered by bramlexs22 last updated on 17/Feb/21…