Important questions based on Time & Work Continues.......
Type 2nd :- Questions based One day work Concept:-
In these
type of questions you just have to read the questions carefully to analyse the
given data in the question and then calculate the required answer with the help
of one day work concept or formula given in this post, which ever you feel more
comfortable to solve the question.
Q10. A and B can do a work in 45 days
and 40 days respectively. They began to do the same work together but A left
the work after some days. If B finishes the remaining work in 23 days then
calculate after how many days did A left the work.
Solution:- First of all you should read this
question carefully and analyse it carefully in such manner:-
Method 1st :- The work in this question is same
means it is constant and always be considered as 1 (one) work only.
worker “A”
can do a piece of work in “45 days”
Therefore
the one day work of worker “A” = (1/45) work
worker “B”
can do a piece of work in “40 days”
Hence the
one day work of worker “B” = (1/40) work
Therefore
work done by worker “B” alone in 23 days = 23 × (1/40) = 23/40 work.
The
remaining work done by workers A and B together = 1 – (23/40) = 17/40 work.
The one day
work of the worker A and B together = (1/45) + (1/40)
= 17/360 work.
Now Number
of days = Total work / One day work.
=
(17/40) / (17/360) = 9 days
Number of
days A and B worked together = Number of days after which A left = 9 days.
Hence Worker
A left the work after 9 days.
Q11. A
& B can do a work in 25 days and 20 days respectively. If A and B
work together for 5 days and then A goes away. Calculate after how many days
will B, be able to finish the remaining work.
Sol. The
work in this question is same means it is constant and always be considered as
1 (one) work only.
worker “A”
can do a piece of work in “25 days”
Therefore
the one day work of worker “A” = (1/25) work
worker “B”
can do a piece of work in “20 days”
Hence the
one day work of worker “B” = (1/20) work
The one day
work of the workers A and B together = (1/25) + (1/20)
= (9/100) work.
The total
work done by the workers A and B together in 5 days = 5 × (9/100) = (9/20)
work.
The
remaining work done by worker B alone = 1 – (9/20) = (11/20) work.
Now Number
of days taken by B = Total work done by B / One day work of B.
= (11/20) / (1/20) = 11 days.
Hence
Worker B will complete the remaining
work in 11 days.
(Note you may say that this is so long but
dear this is the only way to explain the whole concept of the question to you
now its upto you that how fast and short handedly you can solve these type of
questions)
The Various
Questions related to this and other concept which are frequently asked in the
examinations will be presented to your for self study on this blog soon, so
keep visiting and sending your suggestions and requirements too to us through
the forum.
More types
of questions will be followed soon on this blog........................
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