Aptitude - Time and Work - Discussion
Discussion Forum : Time and Work - General Questions (Q.No. 17)
17.
A is 30% more efficient than B. How much time will they, working together, take to complete a job which A alone could have done in 23 days?
Answer: Option
Explanation:
Ratio of times taken by A and B = 100 : 130 = 10 : 13.
Suppose B takes x days to do the work.
Then, 10 : 13 :: 23 : x  x = |
 |
23 x 13 |  |
x = |
299 | . |
| 10 | 10 |
| A's 1 day's work = | 1 | ; |
| 23 |
| B's 1 day's work = | 10 | . |
| 299 |
| (A + B)'s 1 day's work = | |
1 | + | 10 | |
= | 23 | = | 1 | . |
| 23 | 299 | 299 | 13 |
Therefore, A and B together can complete the work in 13 days.
Discussion:
120 comments Page 8 of 12.
Ramesh Naidu said:
1 decade ago
Why can't we take 70% of 23 days? Then we get B's working days right?
But I'm not getting the same result why? Can you explain any one?
But I'm not getting the same result why? Can you explain any one?
Narayan said:
1 decade ago
A = 30% of B.
Now 1 work two Man.
So, A + B = 1-------(1).
=> (30/100)B+B = 1.
=> 3B/10+B = 1.
=> 3B+10B = 10.
=> 13B = 10.
B = 10/13------(2).
(1) & (2) => A = 3/13.
Hence all total = 13 days.
Now 1 work two Man.
So, A + B = 1-------(1).
=> (30/100)B+B = 1.
=> 3B/10+B = 1.
=> 3B+10B = 10.
=> 13B = 10.
B = 10/13------(2).
(1) & (2) => A = 3/13.
Hence all total = 13 days.
Naseem Ahmad Saifi said:
1 decade ago
A' s 1 day work =1/23......(1).
Now A is 30% faster of B.
So A's 1 day work = 130/100*B's 1 day work.
=> A = 13/10*B......(2).
From 1st and 2nd 13/10*B = 1/23 => B's 1 day work = 10/299......(3).
(A+B)'s 1 day work = 1/23+10/299 = 23/299.
So they complete work in 299/23 i.e. 13 days.
Now A is 30% faster of B.
So A's 1 day work = 130/100*B's 1 day work.
=> A = 13/10*B......(2).
From 1st and 2nd 13/10*B = 1/23 => B's 1 day work = 10/299......(3).
(A+B)'s 1 day work = 1/23+10/299 = 23/299.
So they complete work in 299/23 i.e. 13 days.
Durga said:
1 decade ago
Please explain shortcut method.
Nishant said:
1 decade ago
Ratio of times taken by A and B = 100:130 = 10:13.
A alone can do his piece of work in 23 days.
Let B takes x days to complete a given work.
A:B = 10:13.
23:B = 10:13.
B = 299:10.
A's 1 day work = 1:23.
B's 1 day work = 10:299.
(A+B) 's 1 day work = 1:23 + 10:299 = 1:13.
So, together they will complete the work in 13 days.
A alone can do his piece of work in 23 days.
Let B takes x days to complete a given work.
A:B = 10:13.
23:B = 10:13.
B = 299:10.
A's 1 day work = 1:23.
B's 1 day work = 10:299.
(A+B) 's 1 day work = 1:23 + 10:299 = 1:13.
So, together they will complete the work in 13 days.
Dibakar said:
1 decade ago
See A alone can do the work in 23 days which is 30% less than B.
So that means B does the work in 23+0.3*23=29.9.
Now A+B together will take:
1/23+1/29.9 = 529/(23*299) = 1/13.
So it will take both of them 13 days :).
So that means B does the work in 23+0.3*23=29.9.
Now A+B together will take:
1/23+1/29.9 = 529/(23*299) = 1/13.
So it will take both of them 13 days :).
Vivek said:
1 decade ago
A can do whole work in 23 days.
We have ratio 100:130 = 10(b):13(a).
A takes 23x13 to complete a work in 299 days.
Here 299 is total work which A alone can do in 23 days.
So we know total work is 299.
Both can take 10:13 = 23 days.
Total work/together work = 299/23 = 13.
We have ratio 100:130 = 10(b):13(a).
A takes 23x13 to complete a work in 299 days.
Here 299 is total work which A alone can do in 23 days.
So we know total work is 299.
Both can take 10:13 = 23 days.
Total work/together work = 299/23 = 13.
Mehedy said:
1 decade ago
A can 23 days.
B can (23+23*30/100) = 29.9.
A 1 day = 1/23.
B 1 day = 1/29.9.
So (1/23+1/29.9) = 52.9/687.7 = 1/13 = 13.
B can (23+23*30/100) = 29.9.
A 1 day = 1/23.
B 1 day = 1/29.9.
So (1/23+1/29.9) = 52.9/687.7 = 1/13 = 13.
Shakeena said:
1 decade ago
299/10 is the one day work, so reciprocal is the days taken.
Sajid said:
1 decade ago
299/10 to convert 10/299 why please explain?
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