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Category: Permutation and Combination

Suppose-that-7-blue-balls-8-red-balls-and-9-green-balls-should-be-put-into-three-boxes-labeled-1-2-and-3-so-that-any-box-contains-at-least-one-balls-of-each-colour-How-many-ways-can-this-arrangeme

Question Number 119747 by benjo_mathlover last updated on 26/Oct/20 Supposethat7blueballs,8redballsand9greenballsshouldbeputintothreeboxeslabeled1,2and3,sothatanyboxcontainsatleastoneballsofeachcolour.Howmanywayscanthisarrangementbedone? Answered by mr W last…

we-have-15-different-mathematics-books-10-different-physics-books-and-12-different-chemistry-books-we-should-choose-6-books-such-that-they-contain-all-three-kinds-of-books-in-how-many-ways-can-we-d

Question Number 119390 by mr W last updated on 24/Oct/20 wehave15differentmathematicsbooks,10differentphysicsbooksand12differentchemistrybooks.weshouldchoose6bookssuchthattheycontainallthreekindsofbooks.inhowmanywayscanwedothis? Answered by…

Suppose-once-more-we-re-asked-to-choose-four-students-from-high-school-class-of-15-to-form-a-committee-but-this-time-we-have-a-restriction-we-don-t-want-to-committee-to-consist-of-all-seniors-or-al

Question Number 119364 by bobhans last updated on 24/Oct/20 Supposeoncemorewereaskedtochoosefourstudentsfromhighschoolclassof15toformacommitteebutthistimewehavearestriction:wedontwanttocommitteetoconsistofallseniorsoralljuniors.supposethereareeightseniors$${and}\:{seven}\:{juniors}\:{in}\:{the}\:{class}.\:{How}\:{many} \

How-many-sets-of-3-numbers-each-can-be-formed-from-the-numbers-1-2-3-20-if-no-two-consecutive-numbers-are-to-be-in-a-set-

Question Number 118694 by benjo_mathlover last updated on 19/Oct/20 Howmanysetsof3numberseachcanbeformedfromthenumbers{1,2,3,,20}ifnotwoconsecutivenumbersaretobeinaset? Answered by bemath last updated on 19/Oct/20 $$\Rightarrow\:(183)\:=\:\frac{\mathrm{18}×\mathrm{17}×\mathrm{16}}{\mathrm{3}×\mathrm{2}×\mathrm{1}}\:=\:\mathrm{3}×\mathrm{17}×\mathrm{16}=\mathrm{816} \