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(#M40040365) ELITMUS Numerical Ability question Time and Work Keep an EYE

One man builds a wall in 21 months and other one destroys it in 28 months. If they work alternate than in how many months wall will complete?

Asked In Elitmus Dipanshu Singhal (9 years ago)

Unsolved Read Solution (7)

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Read Solution (7) :

aditya saraswat  (9 years ago)

A=100/21=4.761,B=100/28=3.5718(-ve work)
total=4.761-3.5718=1.19047
time to complete 96% of work=96/1.19047=80month due to altenate work total month=2*80=160
now for next one month the work get completed
so total month of work=160+1=161

Is this solution Helpfull? Yes (10) | No (1)  

Ankit  (7 years ago)

This type of questions are very easy to solve guys. So lets do it in a easy way!!!

For our ease, we will think this ques like a story of 2 persons eating and ignoring chocolates.

Take LCM of 21 and 28. It is 84, i.e. 84 chocolates are there for A and B. So the work is to finish these 84 chocolates. A will eat and B will ignore chocolates.

Divide 84 from 21 and 28, i.e, 4 and 3.

Now,our ques becomes very easy to solve.

A will eat 4 chocolates in a day and B will throw(destroy) 3 chocolates in a day.

Acc to ques,
They will work in alternate days,
2nd day work -----> (4-3=1 chocolate)
.
.
.
160th day work --------> 80 chocolates.
Now 4 chocolates left and A will start the work acc to ques.
So he will eat remaining 4 chocolates in 1 day.

Therefore, 160+1= 161 days

Is this solution Helpfull? Yes (10) | No   

rajeev chaubey  (9 years ago)

1 month work of wall making man=w/21
1 month work of wall destroying man =w/28
total work done in 2 month to make wall=(w/21-w/28)=w/84
so,w/84 wall made in=2 month
w work to complete wall=2*84*w/w=168 month
but we know that they are working alternatively.so even days destroying man is working.
it means wall have been already made.
it means thay both worked for 160 month together and then in 161 month wall made
so answer is 161 month

Is this solution Helpfull? Yes (6) | No (1)  

Gaurav Sahu  (9 years ago)

161/7=no remainder i.e. 161

Is this solution Helpfull? Yes (2) | No (1)  

aditya saraswat  (9 years ago)

168 days

Is this solution Helpfull? Yes (1) | No (7)  

deepak  (8 years ago)

161 is the ans

Is this solution Helpfull? Yes (1) | No   

Vikash kumar  (7 years ago)

161 is the correct answer

Is this solution Helpfull? Yes | No   

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