Question and Answers Forum

All Questions      Topic List

Algebra Questions

Previous in All Question      Next in All Question      

Previous in Algebra      Next in Algebra      

Question Number 95277 by bobhans last updated on 24/May/20

Commented by mr W last updated on 24/May/20

((15)/(10×10))+(6/(12×10))=(1/x) x=5 days

$$\frac{\mathrm{15}}{\mathrm{10}×\mathrm{10}}+\frac{\mathrm{6}}{\mathrm{12}×\mathrm{10}}=\frac{\mathrm{1}}{{x}} \\ $$$${x}=\mathrm{5}\:{days} \\ $$

Commented by bobhans last updated on 24/May/20

sir why your method not correct to eq 95232?

$$\mathrm{sir}\:\mathrm{why}\:\mathrm{your}\:\mathrm{method}\:\mathrm{not}\:\mathrm{correct}\:\mathrm{to}\:\mathrm{eq}\:\mathrm{95232}? \\ $$

Commented by mr W last updated on 24/May/20

in 85232 i saw there was need to treat the problem from the ground, therefore i began with lesson one. but now we are in lesson ten, so we don′t need to do like in lesson one. main thing: we have understood and the answer is correct.

$${in}\:\mathrm{85232}\:{i}\:{saw}\:{there}\:{was}\:{need}\:{to}\: \\ $$$${treat}\:{the}\:{problem}\:{from}\:{the}\:{ground}, \\ $$$${therefore}\:{i}\:{began}\:{with}\:{lesson}\:{one}.\:{but} \\ $$$${now}\:{we}\:{are}\:{in}\:{lesson}\:{ten},\:{so}\:{we}\:{don}'{t} \\ $$$${need}\:{to}\:{do}\:{like}\:{in}\:{lesson}\:{one}.\:{main} \\ $$$${thing}:\:{we}\:{have}\:{understood}\:{and}\:{the} \\ $$$${answer}\:{is}\:{correct}. \\ $$

Commented by i jagooll last updated on 24/May/20

i have the problem like that. i will post

$$\mathrm{i}\:\mathrm{have}\:\mathrm{the}\:\mathrm{problem}\:\mathrm{like}\:\mathrm{that}.\:\mathrm{i}\:\mathrm{will} \\ $$$$\mathrm{post} \\ $$

Answered by i jagooll last updated on 24/May/20

say 10m×10 = s 12w×10 = s { ((100m=120w)),((m=(6/5)w)) :} then (15m+6w).x = s ⇒(15×(6/5)w+6w)x = s (24w)x = s ⇒x = (s/(24w)) ...(i) from w = (s/(120)) ⇒ x = (s/(24×((s/(120))))) x = ((120)/(24)) = 5 days

$$\mathrm{say}\:\mathrm{10m}×\mathrm{10}\:=\:\mathrm{s} \\ $$$$\mathrm{12w}×\mathrm{10}\:=\:\mathrm{s}\:\begin{cases}{\mathrm{100m}=\mathrm{120w}}\\{\mathrm{m}=\frac{\mathrm{6}}{\mathrm{5}}\mathrm{w}}\end{cases} \\ $$$$\mathrm{then}\:\left(\mathrm{15m}+\mathrm{6w}\right).{x}\:=\:\mathrm{s} \\ $$$$\Rightarrow\left(\mathrm{15}×\frac{\mathrm{6}}{\mathrm{5}}\mathrm{w}+\mathrm{6w}\right){x}\:=\:\mathrm{s} \\ $$$$\left(\mathrm{24w}\right){x}\:=\:\mathrm{s}\:\Rightarrow{x}\:=\:\frac{\mathrm{s}}{\mathrm{24w}}\:...\left(\mathrm{i}\right) \\ $$$$\mathrm{from}\:\mathrm{w}\:=\:\frac{\mathrm{s}}{\mathrm{120}}\:\Rightarrow\:{x}\:=\:\frac{\mathrm{s}}{\mathrm{24}×\left(\frac{\mathrm{s}}{\mathrm{120}}\right)} \\ $$$${x}\:=\:\frac{\mathrm{120}}{\mathrm{24}}\:=\:\mathrm{5}\:{days} \\ $$$$ \\ $$

Commented by bobhans last updated on 24/May/20

dear prof mr w. please check my answer

$$\mathrm{dear}\:\mathrm{prof}\:\mathrm{mr}\:\mathrm{w}.\:\mathrm{please}\:\mathrm{check}\:\mathrm{my}\:\mathrm{answer} \\ $$

Commented by mr W last updated on 24/May/20

if your answer is also “5 days”, then correct.

$${if}\:{your}\:{answer}\:{is}\:{also}\:``\mathrm{5}\:{days}'',\:{then} \\ $$$${correct}. \\ $$

Commented by mr W last updated on 24/May/20

we can also solve it just using logic. 10 men in 10 days do the same as 12 women in 10 days, that means a man is so much as 1.2 women. 15 men and 6 women are the same as 15×1.2+6=24 women. so the question is how long need 24 women? since 12 women need 10 days, so 24 women need 5 days. this is the answer which you can also get even you don′t know how to solve equations.

$${we}\:{can}\:{also}\:{solve}\:{it}\:{just}\:{using}\:{logic}. \\ $$$$\mathrm{10}\:{men}\:{in}\:\mathrm{10}\:{days}\:{do}\:{the}\:{same}\:{as} \\ $$$$\mathrm{12}\:{women}\:{in}\:\mathrm{10}\:{days},\:{that}\:{means} \\ $$$${a}\:{man}\:{is}\:{so}\:{much}\:{as}\:\mathrm{1}.\mathrm{2}\:{women}. \\ $$$$\mathrm{15}\:{men}\:{and}\:\mathrm{6}\:{women}\:{are}\:{the}\:{same} \\ $$$${as}\:\mathrm{15}×\mathrm{1}.\mathrm{2}+\mathrm{6}=\mathrm{24}\:{women}.\:{so}\:{the} \\ $$$${question}\:{is}\:{how}\:{long}\:{need}\:\mathrm{24}\:{women}? \\ $$$${since}\:\mathrm{12}\:{women}\:{need}\:\mathrm{10}\:{days},\:{so}\:\mathrm{24} \\ $$$${women}\:{need}\:\mathrm{5}\:{days}.\:{this}\:{is}\:{the}\:{answer} \\ $$$${which}\:{you}\:{can}\:{also}\:{get}\:{even}\:{you}\:{don}'{t} \\ $$$${know}\:{how}\:{to}\:{solve}\:{equations}. \\ $$

Commented by bobhans last updated on 24/May/20

my method same with your answer 10 men →10 day 12women →10 day 15 men + 6 women →x day (1/x) = ((15)/(10×10)) + (6/(12×10)) but i compare to qn 95232 why not correct

$$\mathrm{my}\:\mathrm{method}\:\mathrm{same}\:\mathrm{with}\:\mathrm{your}\:\mathrm{answer} \\ $$$$\mathrm{10}\:\mathrm{men}\:\rightarrow\mathrm{10}\:\mathrm{day} \\ $$$$\mathrm{12women}\:\rightarrow\mathrm{10}\:\mathrm{day} \\ $$$$\mathrm{15}\:\mathrm{men}\:+\:\mathrm{6}\:\mathrm{women}\:\rightarrow\mathrm{x}\:\mathrm{day} \\ $$$$\frac{\mathrm{1}}{\mathrm{x}}\:=\:\frac{\mathrm{15}}{\mathrm{10}×\mathrm{10}}\:+\:\frac{\mathrm{6}}{\mathrm{12}×\mathrm{10}} \\ $$$$\mathrm{but}\:\mathrm{i}\:\mathrm{compare}\:\mathrm{to}\:\mathrm{qn}\:\mathrm{95232}\:\mathrm{why}\:\mathrm{not}\:\mathrm{correct} \\ $$

Answered by Farruxjano last updated on 24/May/20

Solution: Let: the man′s speed−v_1 , the woman′s speed−v_2 , the work−S. So, we get from the the task: 10v_1 =(S/(10)) ⇒ v_1 =(S/(100)) and 12v_2 =(S/(10)) ⇒ v_2 =(S/(120)) we must calculate: 15v_1 +6v_2 = =15∙(S/(100))+6∙(S/(120))=((3S)/(20))+(S/(20))=((4S)/(20))=(S/5) But: (S/5)<S ⇒ So, they don′t cope!

$$\boldsymbol{{Solution}}:\:\boldsymbol{{Let}}:\:\boldsymbol{{the}}\:\boldsymbol{{man}}'\boldsymbol{{s}}\:\boldsymbol{{speed}}−\boldsymbol{{v}}_{\mathrm{1}} , \\ $$$$\boldsymbol{{the}}\:\boldsymbol{{woman}}'\boldsymbol{{s}}\:\boldsymbol{{speed}}−\boldsymbol{{v}}_{\mathrm{2}} ,\:\boldsymbol{{the}}\:\boldsymbol{{work}}−\boldsymbol{{S}}. \\ $$$$\boldsymbol{{So}},\:\boldsymbol{{we}}\:\boldsymbol{{get}}\:\boldsymbol{{from}}\:\boldsymbol{{the}}\:\boldsymbol{{the}}\:\boldsymbol{{task}}: \\ $$$$\mathrm{10}\boldsymbol{{v}}_{\mathrm{1}} =\frac{\boldsymbol{{S}}}{\mathrm{10}}\:\Rightarrow\:\boldsymbol{{v}}_{\mathrm{1}} =\frac{\boldsymbol{{S}}}{\mathrm{100}}\:\boldsymbol{{and}}\:\mathrm{12}\boldsymbol{{v}}_{\mathrm{2}} =\frac{\boldsymbol{{S}}}{\mathrm{10}}\:\Rightarrow\:\boldsymbol{{v}}_{\mathrm{2}} =\frac{\boldsymbol{{S}}}{\mathrm{120}} \\ $$$$\boldsymbol{{we}}\:\boldsymbol{{must}}\:\boldsymbol{{calculate}}:\:\mathrm{15}\boldsymbol{{v}}_{\mathrm{1}} +\mathrm{6}\boldsymbol{{v}}_{\mathrm{2}} = \\ $$$$=\mathrm{15}\centerdot\frac{\boldsymbol{{S}}}{\mathrm{100}}+\mathrm{6}\centerdot\frac{\boldsymbol{{S}}}{\mathrm{120}}=\frac{\mathrm{3}\boldsymbol{{S}}}{\mathrm{20}}+\frac{\boldsymbol{{S}}}{\mathrm{20}}=\frac{\mathrm{4}\boldsymbol{{S}}}{\mathrm{20}}=\frac{\boldsymbol{{S}}}{\mathrm{5}}\:\boldsymbol{{But}}: \\ $$$$\frac{\boldsymbol{{S}}}{\mathrm{5}}<\boldsymbol{{S}}\:\:\:\:\:\:\Rightarrow\:\:\:\:\:\:\boldsymbol{{So}},\:\boldsymbol{{they}}\:\boldsymbol{{don}}'\boldsymbol{{t}}\:\boldsymbol{{cope}}! \\ $$

Commented by bobhans last updated on 24/May/20

what the meaning don′t cope?

$$\mathrm{what}\:\mathrm{the}\:\mathrm{meaning}\:\mathrm{don}'\mathrm{t}\:\mathrm{cope}? \\ $$

Commented by Farruxjano last updated on 24/May/20

They cannot complete in time! sorry I said that i don′t know English perfect :)

$$\boldsymbol{{They}}\:\boldsymbol{{cannot}}\:\boldsymbol{{complete}}\:\boldsymbol{{in}}\:\boldsymbol{{time}}! \\ $$$$\boldsymbol{{sorry}}\:\boldsymbol{{I}}\:\boldsymbol{{said}}\:\boldsymbol{{that}}\:\boldsymbol{{i}}\:\boldsymbol{{don}}'\boldsymbol{{t}}\:\boldsymbol{{know}}\:\boldsymbol{{English}} \\ $$$$\left.\boldsymbol{{perfect}}\::\right) \\ $$

Commented by mr W last updated on 24/May/20

even with only one man or one woman the job can be finished, that′s for sure. it′s only a question how long they need. so what do you mean with “they can not complete in time”?

$${even}\:{with}\:{only}\:{one}\:{man}\:{or}\:{one}\:{woman} \\ $$$${the}\:{job}\:{can}\:{be}\:{finished},\:{that}'{s}\:{for}\:{sure}. \\ $$$${it}'{s}\:{only}\:{a}\:{question}\:{how}\:{long}\:{they}\:{need}. \\ $$$${so}\:{what}\:{do}\:{you}\:{mean}\:{with}\:``{they}\:{can} \\ $$$${not}\:{complete}\:{in}\:{time}''? \\ $$

Terms of Service

Privacy Policy

Contact: info@tinkutara.com