CAT Question Bank  Time & Work

@rowdyrathore could u plzz explain bcz mine is 20

@Ishita 22.5 is the right answer.
A does 3x and B does x amount of work in a given amount of time.
as work is inversely proportional to the time taken, A takes t days and B takes 3t days to complete a given amount of work.
we know 3t  t = 60 days
t = 30 days
So A takes 30 days and B takes 30 + 60 = 90 daysTogether, 1/30 + 1/90 = 4/90 of work will be completed and it will take 90/4 = 22.5 days to finish the work together.

@Ishita 120 is correct. Can you share your detailed approach so that others will benefit :)

@RowdyRathore answer/explaination ??

@RowdyRathore Answer/Solution??

@rowdyrathore approach/solution?

@rowdyrathore, at first they ran at full capacities for 3 minutes, then they ran at reduced capacities for 1 minute. Hence, they started again after 4 minutes.

2nd method
after calculating we got 12x660
we can equate this with 8x.
=>12x660=8x
=>4x=660
=>x=165.

mandays method
20m+30b=1...1
24m+18b=1...2
by equating 1 and 2
we get
2m=7b...3
using equation 3
(2m+3b)10=(2m+1b)x
100b=8bx
or x=12.5.

2(a+b+c)=1/72+1/120+1/90
=>a+b+c=1/60
a=1/601/120
=1/120
=120 days.

@rowdyrathore x takes 43=12 days to complete the job=> work done in 1 day=1/12
y takes36=18 days to complete the job=> work done in 1 day=1/18
z takes 52=10 days to complete the job=> work done in 1 day=1/10
Work done by all of them in 3 days=3(1/12+1/18+1/10)
=3*(15+10+18)/180
=43/60
work left=17/60
if y takes a days,
work done=a1/18=17/60
=>a=(1718)/60
=>a=5.1 days

@rowdyrathore 15 days a alone can do the job.

@rowdyrathore by taking lcm of 14 and 21 we get 
3 units done by a and 2 units done by b
last 3 days b did 3*2= 6 units of work.
a nd b did 426=36 units of work together.
so 36/5=7.2 days by both
total days =7.2+3=10.2 days.

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@rowdyrathore Can you please provide the solution to this question.