Aptitude - Time and Work - Discussion
Discussion Forum : Time and Work - General Questions (Q.No. 4)
4.
A is thrice as good as workman as B and therefore is able to finish a job in 60 days less than B. Working together, they can do it in:
Answer: Option
Explanation:
Ratio of times taken by A and B = 1 : 3.
The time difference is (3 - 1) 2 days while B take 3 days and A takes 1 day.
If difference of time is 2 days, B takes 3 days.
| If difference of time is 60 days, B takes |  |
3 | x 60 |  |
= 90 days. |
| 2 |
So, A takes 30 days to do the work.
| A's 1 day's work = | 1 |
| 30 |
| B's 1 day's work = | 1 |
| 90 |
| (A + B)'s 1 day's work = | |
1 | + | 1 | |
= | 4 | = | 2 |
| 30 | 90 | 90 | 45 |
 A and B together can do the work in |
45 | = 22 | 1 | days. |
| 2 | 2 |
Discussion:
281 comments Page 19 of 29.
Mahesh said:
9 years ago
Let consider B can do work in n days.
1 days work of B = 1/n.
So, A = n - 60.
1 day work of A =1/ (n - 60).
As given A = 3b.
1/ (n - 60) = 3 * (1/n).
n = 90.
B can do work in 90 days.
So A can do in 30 days.
Both = (1/30) + (1/90).
= 22 (1/2).
1 days work of B = 1/n.
So, A = n - 60.
1 day work of A =1/ (n - 60).
As given A = 3b.
1/ (n - 60) = 3 * (1/n).
n = 90.
B can do work in 90 days.
So A can do in 30 days.
Both = (1/30) + (1/90).
= 22 (1/2).
Insane said:
9 years ago
Let A be X where as b = 3x.
So,
3x - x = 60.
x = 30.
a = 30, b = 90.
Together they can do the work in 22 (1/2) days.
So,
3x - x = 60.
x = 30.
a = 30, b = 90.
Together they can do the work in 22 (1/2) days.
Priya said:
9 years ago
Please say me any shortcut methods to solve this problem.
Anonymous said:
9 years ago
Hello friends,
I just want to clear out something and that is according to the formula given. Here the answer is not correct.
There has been a mistake and that is it is wrongly solved becomes as the question goes hereby,
1) A is thrice as good as B so the ratio would be like 3:1. But it has been mentioned as 1:3 which is wrong according to my perception.
So please make it correct or give the correct sort of explanation to prove me wrong.
I just want to clear out something and that is according to the formula given. Here the answer is not correct.
There has been a mistake and that is it is wrongly solved becomes as the question goes hereby,
1) A is thrice as good as B so the ratio would be like 3:1. But it has been mentioned as 1:3 which is wrong according to my perception.
So please make it correct or give the correct sort of explanation to prove me wrong.
SscASPIRANT said:
9 years ago
Hi guys
Here is a trick to solve it.
If B = 1, A = 3,
Therefore efficiency is A : B = 3 : 1.
Now, 60 days less means the difference of their efficiency.
2 ---> 60
1 ---> 30
Now you got 30.
A = 3 * 30 = 90,
B = 1 * 30 = 30,
LCM = 90.
Which is total work and total days = total work/total efficiency.
T.D = 90/4 = 45/2 = 22 (1/2)days.
Here is a trick to solve it.
If B = 1, A = 3,
Therefore efficiency is A : B = 3 : 1.
Now, 60 days less means the difference of their efficiency.
2 ---> 60
1 ---> 30
Now you got 30.
A = 3 * 30 = 90,
B = 1 * 30 = 30,
LCM = 90.
Which is total work and total days = total work/total efficiency.
T.D = 90/4 = 45/2 = 22 (1/2)days.
Vaishnavi said:
9 years ago
Thanks @Sheetal it is best trick.
Mohin Uddin Mizan said:
9 years ago
Let B takes X days to the work.
Then B's 1 day's work = 1/x and A's 1/3x.
ACQ, 1/x - 1/3x = 60, So, x = 1/90.
As the difference is 60, so A needed 90 - 60 = 30 days.
(A + B)'s 1 day's work = 1/90 + 1/30 = 2/45.
So, to do the total work they need 45/2 or 22(1/2).
Then B's 1 day's work = 1/x and A's 1/3x.
ACQ, 1/x - 1/3x = 60, So, x = 1/90.
As the difference is 60, so A needed 90 - 60 = 30 days.
(A + B)'s 1 day's work = 1/90 + 1/30 = 2/45.
So, to do the total work they need 45/2 or 22(1/2).
Soniya said:
9 years ago
Let t1 &t2 are time taken by A and B.
w1 & w2 are work done by A and B.
Ratio of the time taken by A and B =1 : 3.
Then, A = x, B = 3x (x is some constant).
We know that t1 = t2 - 60 (A takes 60 days less than B).
t2 - t1 = 60
3x - x = 60 (t1 = x, t2 = 3x)
x = 30.
Then t1=30 and t2 = 90.
Total work done by A& B(W) = w1 + w2.
W =1/t1 + 1/t2.
= 1/30 + 1/90 = 2/45.
Then time taken by A&B to finish the work is 45/2days.
w1 & w2 are work done by A and B.
Ratio of the time taken by A and B =1 : 3.
Then, A = x, B = 3x (x is some constant).
We know that t1 = t2 - 60 (A takes 60 days less than B).
t2 - t1 = 60
3x - x = 60 (t1 = x, t2 = 3x)
x = 30.
Then t1=30 and t2 = 90.
Total work done by A& B(W) = w1 + w2.
W =1/t1 + 1/t2.
= 1/30 + 1/90 = 2/45.
Then time taken by A&B to finish the work is 45/2days.
Devendra kumar said:
9 years ago
Please tell me the easiest solution of this problem. Like LCM method.
Udhay said:
9 years ago
I can't understand it. Please someone help me.
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