Question Number 131876 by I want to learn more last updated on 09/Feb/21
Answered by EDWIN88 last updated on 09/Feb/21
$$\left(\mathrm{i}\right)\:\mathrm{C}_{\mathrm{8}} ^{\mathrm{10}} \:=\:\frac{\mathrm{10}×\mathrm{9}}{\mathrm{2}×\mathrm{1}}=\mathrm{45}\: \\ $$
Answered by liberty last updated on 09/Feb/21
$$\left(\mathrm{ii}\right)\:\mathrm{C}_{\mathrm{8}−\mathrm{3}} ^{\mathrm{10}−\mathrm{3}} \:=\:\mathrm{C}_{\mathrm{5}} ^{\mathrm{7}} \:=\:\frac{\mathrm{7}×\mathrm{6}}{\mathrm{2}×\mathrm{1}}\:=\:\mathrm{21}\: \\ $$
Answered by physicstutes last updated on 10/Feb/21
$$\mathrm{number}\:\mathrm{of}\:\mathrm{questions}\:\mathrm{required}\:\mathrm{to}\:\mathrm{answer}\:=\:\mathrm{8} \\ $$$$\mathrm{total}\:=\:\mathrm{10} \\ $$$$\left(\mathrm{i}\right)\:^{\mathrm{10}} \mathrm{C}_{\mathrm{8}} \:=\:\frac{\mathrm{10}!}{\mathrm{2}!\mathrm{8}!} \\ $$$$\left(\mathrm{ii}\right)\:^{\mathrm{7}} \mathrm{C}_{\mathrm{5}} \:=\:\frac{\mathrm{7}!}{\mathrm{2}!\mathrm{5}!} \\ $$$$\left(\mathrm{iii}\right)\:\mathrm{if}\:\mathrm{he}\:\mathrm{answers}\:\mathrm{first}\:\mathrm{question}\:\mathrm{or}\:\mathrm{2nd}\:\mathrm{question}\:=\:^{\mathrm{9}} \mathrm{C}_{\mathrm{7}} \\ $$$$\:\mathrm{if}\:\mathrm{he}\:\mathrm{answers}\:\mathrm{first}\:\mathrm{two}\:=\:^{\mathrm{8}} \mathrm{C}_{\mathrm{6}} \\ $$$$\Rightarrow\:\mathrm{total}\:=\:\mathrm{2}\left(^{\mathrm{9}} \mathrm{C}_{\mathrm{7}} \right)\:+\:^{\mathrm{8}} \mathrm{C}_{\mathrm{6}} \\ $$
Commented by I want to learn more last updated on 23/Feb/21
$$\mathrm{Thanks}\:\mathrm{sirs}.\:\mathrm{I}\:\mathrm{appreciate}. \\ $$