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If 18 identical machines required 40 days to complete a job, how many

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Joined: 25 Dec 2018
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Concentration: General Management, Finance
GMAT 1: 590 Q48 V23
GPA: 3.4
WE: Engineering (Consulting)
If 18 identical machines required 40 days to complete a job, how many  [#permalink]

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New post 05 Mar 2019, 10:15
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  45% (medium)

Question Stats:

50% (01:20) correct 50% (02:01) wrong based on 14 sessions

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If 18 identical machines required 40 days to complete a job, how many fewer days would have been required to do the job if 54 additional machines of the same type had been used since the beginning?

A. 10 days
B. 40/3 days
C. 16 days
D. 80/3 days
E. 30 days
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Re: If 18 identical machines required 40 days to complete a job, how many  [#permalink]

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New post 05 Mar 2019, 21:50
18 machines did (1/40)th work in a day, then 72 ie (54+18) machines did x work in a day
x = 1/10 , ie 10 days. ( Use proportionals logic )
So difference is 30 days
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Re: If 18 identical machines required 40 days to complete a job, how many  [#permalink]

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New post 05 Mar 2019, 22:50
I have a tricky question.. help me out

Of the 50 students in a class who took the test , the median score is 74. If the average of 21 students below the median is 80 and the average of 24 students above the median is 96. Then find out the average of the entire 50 students????

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Re: If 18 identical machines required 40 days to complete a job, how many  [#permalink]

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New post 05 Mar 2019, 22:52
18 Machines - Rate 1/40 hence 1 machine takes - 1/(40*18).
72 Machines takes 1/(40*18)*72 = 10 days. So 30 days less
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Re: If 18 identical machines required 40 days to complete a job, how many  [#permalink]

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New post 05 Mar 2019, 22:59
tushki23 wrote:
I have a tricky question.. help me out

Of the 50 students in a class who took the test , the median score is 74. If the average of 21 students below the median is 80 and the average of 24 students above the median is 96. Then find out the average of the entire 50 students????

Posted from my mobile device


My solution is (21*80)+(24*96)+(5*74)/50 will get you the average of 50. 45 Students are either above or below the median, so rest 5 will be on the median.
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Re: If 18 identical machines required 40 days to complete a job, how many  [#permalink]

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New post 05 Mar 2019, 23:37
1
tushki23 wrote:
I have a tricky question.. help me out

Of the 50 students in a class who took the test , the median score is 74. If the average of 21 students below the median is 80 and the average of 24 students above the median is 96. Then find out the average of the entire 50 students????

Posted from my mobile device


I'm thinking out loud, so help me understand.
If median is 74, then all students scoring below the median should get less than 74, and if thats the case, how can average be above the median, ie, 80.
How is this possible?
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Re: If 18 identical machines required 40 days to complete a job, how many  [#permalink]

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New post 05 Mar 2019, 23:43
I checked out again.. I flipped on the values.. it is actually mean of 21 students is 60 and the other 24 students is 96.. now it will make sense to you

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Re: If 18 identical machines required 40 days to complete a job, how many  [#permalink]

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New post 05 Mar 2019, 23:50
saad2019 wrote:
tushki23 wrote:
I have a tricky question.. help me out

Of the 50 students in a class who took the test , the median score is 74. If the average of 21 students below the median is 80 and the average of 24 students above the median is 96. Then find out the average of the entire 50 students????

Posted from my mobile device


I'm thinking out loud, so help me understand.
If median is 74, then all students scoring below the median should get less than 74, and if thats the case, how can average be above the median, ie, 80.
How is this possible?

You are absolutely correct. didn't consider that.
GMAT Club Bot
Re: If 18 identical machines required 40 days to complete a job, how many   [#permalink] 05 Mar 2019, 23:50
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