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06 Oct 2019, 21:10
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B
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
25%
(medium)
Question Stats:
82% (02:13) correct
18%
(02:25)
wrong
based on 296
sessions
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Tom, Amanda and Harry working alone can finish a task in 4, 6, and 12 hours respectively. Tom, Amanda and Harry start working together and work for 1 hour, then Tom left and then Amanda and Harry work together for 1 hour, then Amanda left and the rest of the work is done by Harry alone. If the task was started at 10:00 am, then at what time does the task get completed?
(A) 2:30 pm
(B) 3:00 pm
(C) 3:30 pm
(D) 4:00 pm
(E) 4:30 pm
(A) 2:30 pm
(B) 3:00 pm
(C) 3:30 pm
(D) 4:00 pm
(E) 4:30 pm
06 Oct 2019, 21:36
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Angad97
Tom can finish the work in 4 hours, and he works for ONE hour, so he does \(\frac{1}{4}^{th}\) of the work..
Amanda can finish the work in 6 hours, and she works for first TWO hours, so she does \(\frac{2}{6} =\frac{1}{3}^rd\) of the work..
Remaining work = \(1-\frac{1}{4}-\frac{1}{3}=\frac{5}{12}\) is done by Harry..
Harry completes the work in 12 hours, so he will complete \(\frac{5}{12}^{th}\) of work in \(12*\frac{5}{12}=5\) hrs
So, the work will finish at 10:00+5hrs=3:00 pm..
B
12 May 2020, 07:53
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Angad97
SOLUTION
so take the lcm of 4,6,12
which is 12 this is work lets assume
rate=work /time
so
tom=(12/4)=3
amanda=(12/6)=2
harry=(12/12)=1
now
add the rates they said first 1 hour t,a ,h worked together
3+2+1=6
this is from 10 am to 11 am
now tom leaves
so a and h
its 2+1=3
from 11am to 12 am
so from 10am to 12 am the rate of work done is 6+3=9
now we should know how much left over work is done by harry (so do total work( minus -)the work from 10am to 12 am)
now as we assume the work to be 12 the trick is do 12-9=3(try this with any combination of numbers ull get correct ans )
now the rate harry is 1 and time=work/rate => 3/1
so now its 3 hours from 12 am
and is c 3:00 am
