Question Number 7881 by Rasheed Soomro last updated on 23/Sep/16
$${A}\:{gets}\:\mathrm{1}/\mathrm{5}\:\:{of}\:\:{some}\:\:{amount}, \\ $$$${B}\:\:{gets}\:\mathrm{1}/\mathrm{3}\:\:{of}\:\:{remaining},\:{C} \\ $$$${gets}\:\mathrm{1}/\mathrm{6}\:{of}\:{remaining},\:{D}\:{gets} \\ $$$$\mathrm{1}/\mathrm{7}\:\:{of}\:\:{remaining}\:\:{and}\:{E}\:{gets} \\ $$$${rest}\:{of}\:{amount}.\:{What}\:{fraction} \\ $$$${gets}\:{E}\:? \\ $$
Commented by sandy_suhendra last updated on 23/Sep/16
$${A}=\frac{\mathrm{1}}{\mathrm{5}} \\ $$$${B}=\frac{\mathrm{1}}{\mathrm{3}}\:\left[\mathrm{1}−\frac{\mathrm{1}}{\mathrm{5}}\right]=\:\frac{\mathrm{4}}{\mathrm{15}} \\ $$$${C}=\frac{\mathrm{1}}{\mathrm{6}}\left[\mathrm{1}−\frac{\mathrm{1}}{\mathrm{5}}−\frac{\mathrm{4}}{\mathrm{15}}\right]=\frac{\mathrm{4}}{\mathrm{45}} \\ $$$${D}=\frac{\mathrm{1}}{\mathrm{7}}\left[\mathrm{1}−\frac{\mathrm{1}}{\mathrm{5}}−\frac{\mathrm{4}}{\mathrm{15}}−\frac{\mathrm{4}}{\mathrm{45}}\right]=\frac{\mathrm{20}}{\mathrm{315}} \\ $$$${E}=\mathrm{1}−\frac{\mathrm{1}}{\mathrm{5}}−\frac{\mathrm{4}}{\mathrm{15}}−\frac{\mathrm{4}}{\mathrm{45}}−\frac{\mathrm{20}}{\mathrm{315}}=\frac{\mathrm{120}}{\mathrm{315}}=\frac{\mathrm{8}}{\mathrm{21}} \\ $$$${or} \\ $$$${A}=\frac{\mathrm{1}}{\mathrm{5}}\:{so}\:{the}\:{remaining}\:=\:\mathrm{1}−\frac{\mathrm{1}}{\mathrm{5}}=\frac{\mathrm{4}}{\mathrm{5}} \\ $$$${B}=\frac{\mathrm{1}}{\mathrm{3}}×\frac{\mathrm{4}}{\mathrm{5}}=\frac{\mathrm{4}}{\mathrm{15}} \\ $$$${C}=\frac{\mathrm{1}}{\mathrm{6}}×\frac{\mathrm{4}}{\mathrm{5}}=\frac{\mathrm{2}}{\mathrm{15}} \\ $$$${D}=\frac{\mathrm{1}}{\mathrm{7}}×\frac{\mathrm{4}}{\mathrm{5}}=\frac{\mathrm{4}}{\mathrm{35}} \\ $$$${E}=\frac{\mathrm{4}}{\mathrm{5}}−\frac{\mathrm{4}}{\mathrm{15}}−\frac{\mathrm{2}}{\mathrm{15}}−\frac{\mathrm{4}}{\mathrm{35}}=\frac{\mathrm{30}}{\mathrm{105}}=\frac{\mathrm{2}}{\mathrm{7}} \\ $$$${but}\:{I}\:{don}'{t}\:{know}\:{which}\:{one}\:{is}\:{true} \\ $$
Commented by Rasheed Soomro last updated on 27/Sep/16
$$ \\ $$$$ \\ $$$${I}\:{think}\:{your}\:{first}\:{answer}\:{is}\:{correct}. \\ $$$${I}\:{have}\:{done}\:{it}\:{slightly}\:{in}\:{defferent} \\ $$$${way}. \\ $$$$ \\ $$$${A}\:\:{gets}\:\frac{\mathrm{1}}{\mathrm{5}} \\ $$$${Remaining}\:{after}\:{A}=\mathrm{1}−\frac{\mathrm{1}}{\mathrm{5}}=\frac{\mathrm{4}}{\mathrm{5}} \\ $$$${B}\:{gets}\:\:\:\:\frac{\mathrm{4}}{\mathrm{5}}×\frac{\mathrm{1}}{\mathrm{3}}=\frac{\mathrm{4}}{\mathrm{15}} \\ $$$${Remaining}\:\:{after}\:{B}=\frac{\mathrm{4}}{\mathrm{5}}−\frac{\mathrm{4}}{\mathrm{15}}=\frac{\mathrm{12}−\mathrm{4}}{\mathrm{15}}=\frac{\mathrm{8}}{\mathrm{15}} \\ $$$${C}\:\:{gets}\:\frac{\mathrm{8}}{\mathrm{15}}×\frac{\mathrm{1}}{\mathrm{6}}=\frac{\mathrm{4}}{\mathrm{45}} \\ $$$${Remaining}\:\:{after}\:{C}=\frac{\mathrm{8}}{\mathrm{15}}−\frac{\mathrm{4}}{\mathrm{45}}=\frac{\mathrm{24}−\mathrm{4}}{\mathrm{45}}=\frac{\mathrm{20}}{\mathrm{45}}=\frac{\mathrm{4}}{\mathrm{9}} \\ $$$${D}\:{gets}\:\frac{\mathrm{4}}{\mathrm{9}}×\frac{\mathrm{1}}{\mathrm{7}}=\frac{\mathrm{4}}{\mathrm{63}} \\ $$$${Remaining}\:{after}\:{D}=\frac{\mathrm{4}}{\mathrm{9}}−\frac{\mathrm{4}}{\mathrm{63}}=\frac{\mathrm{28}−\mathrm{4}}{\mathrm{63}}=\frac{\mathrm{24}}{\mathrm{63}}=\frac{\mathrm{8}}{\mathrm{21}} \\ $$$${E}\:{gets}\:\:\frac{\mathrm{8}}{\mathrm{21}}×\mathrm{1}=\frac{\mathrm{8}}{\mathrm{21}}\:\:\:\left[\:{D}\:{gets}\:{whole}\:{of}\:{the}\:{remaining}\right] \\ $$$${E}\:{gets}\:{fraction}\:\frac{\mathrm{8}}{\mathrm{21}} \\ $$
Answered by FilupSmith last updated on 23/Sep/16
$${Total}=\mathrm{1} \\ $$$$\mathrm{1}=\frac{\mathrm{1}}{\mathrm{5}}+\left(\frac{\mathrm{1}}{\mathrm{5}}\right)\frac{\mathrm{1}}{\mathrm{3}}+\left(\frac{\mathrm{1}}{\mathrm{5}}×\frac{\mathrm{1}}{\mathrm{3}}\right)\frac{\mathrm{1}}{\mathrm{6}}+\left(\frac{\mathrm{1}}{\mathrm{5}}×\frac{\mathrm{1}}{\mathrm{3}}×\frac{\mathrm{1}}{\mathrm{6}}×\frac{\mathrm{1}}{\mathrm{7}}\right)+{E} \\ $$$$\mathrm{1}=\frac{\mathrm{1}}{\mathrm{5}}+\frac{\mathrm{1}}{\mathrm{15}}+\frac{\mathrm{1}}{\mathrm{90}}+\frac{\mathrm{1}}{\mathrm{540}}+{E} \\ $$$$\mathrm{1}=\frac{\mathrm{88}}{\mathrm{315}}+{E} \\ $$$${E}=\frac{\mathrm{227}}{\mathrm{315}} \\ $$$$\: \\ $$$${I}\:{am}\:{unsure}\:{if}\:{i}\:{answered}\:{correct} \\ $$