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# A contractor undertakes to do a job within 100 days and hires 10 peopl

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Manager
Joined: 31 Jul 2017
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Location: Tajikistan
Re: A contractor undertakes to do a job within 100 days and hires 10 peopl  [#permalink]

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14 Sep 2018, 06:13
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A contractor undertakes to do a job within 100 days and hires 10 people to do it. After 20 days, he realizes that one fourth of the work is done so he fires 2 people. In how many more days will the work get over?
(A) 60
(B) 70
(C) 75
(D) 80
(E) 100

A,D,E are out for obvious reasons. Now, we are left with B and C. If contractor doesn't fire any worker, then it will take them 60 days, but since he is firing 2 workers (or 20%), the work will be slowed down by 20% as well. So 60 days is 80%, 75 days is 100%
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Concentration: Strategy, Organizational Behavior
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Re: A contractor undertakes to do a job within 100 days and hires 10 peopl  [#permalink]

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16 Sep 2018, 11:21
We can also use the percentage method if someone is comfortable with it.

So we know that 25% (one fourth) work is done in 20 days. Which means that 1.25% work is done in a day. And .125% work was done by 1 person (since there were 10 people ). Now we have 8 people and not 10 so the total work done in a day will be .125%*8 = 1%. We know that since 3/4 work is done which is 75% and 1% work is done on daily basis it will take 75 more days. Hence Answer is (c)
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Re: A contractor undertakes to do a job within 100 days and hires 10 peopl  [#permalink]

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16 Sep 2018, 11:22
We can also use the percentage method if someone is comfortable with it.

So we know that 25% (one fourth) work is done in 20 days. Which means that 1.25% work is done in a day. And .125% work was done by 1 person (since there were 10 people ). Now we have 8 people and not 10 so the total work done in a day will be .125%*8 = 1%. We know that since 3/4 work is done which is 75% and 1% work is done on daily basis it will take 75 more days. Hence Answer is (c)
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Re: A contractor undertakes to do a job within 100 days and hires 10 peopl  [#permalink]

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26 Jul 2019, 22:25
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santorasantu wrote:
Bunuel wrote:
A contractor undertakes to do a job within 100 days and hires 10 people to do it. After 20 days, he realizes that one fourth of the work is done so he fires 2 people. In how many more days will the work get over?

(A) 60
(B) 70
(C) 75
(D) 80
(E) 100

Kudos for a correct solution.

Total work content = 100*10 = 1000[units]

work done in 20 days by 10 people = 250[units]
20 days --- 250[units] ---10[people]
x days ---- 750[units] ---- 8[people]

x = 20*(750/250)*(10/8) = 75[days]

C

Shouldn't the worth done by 20 ppl in 10 days be 200 and not 250? Where am I going wrong ?
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Re: A contractor undertakes to do a job within 100 days and hires 10 peopl  [#permalink]

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27 Jul 2019, 02:23
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Hi Rajeet123

A contractor undertakes to do a job within 100 days and hires 10 people to do it. After 20 days, he realizes that one fourth of the work is done so he fires 2 people. In how many more days will the work get over?

total work content is 1000[units] and 1/4th of this work content is 250[units] which took 10 people 20 days.
so it is 250 units.

Hope this is clear
Manager
Joined: 15 Aug 2017
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Re: A contractor undertakes to do a job within 100 days and hires 10 peopl  [#permalink]

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27 Jul 2019, 02:25
santorasantu wrote:
Hi Rajeet123

A contractor undertakes to do a job within 100 days and hires 10 people to do it. After 20 days, he realizes that one fourth of the work is done so he fires 2 people. In how many more days will the work get over?

total work content is 1000[units] and 1/4th of this work content is 250[units] which took 10 people 20 days.
so it is 250 units.

Hope this is clear

How can I be so silly! Thanks a tonne!
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Re: A contractor undertakes to do a job within 100 days and hires 10 peopl   [#permalink] 27 Jul 2019, 02:25

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