Aptitude - Time and Work - Discussion
Discussion Forum : Time and Work - General Questions (Q.No. 29)
29.
A and B can do a job together in 7 days. A is 1
times as efficient as B. The same job can be done by A alone in :
times as efficient as B. The same job can be done by A alone in :Answer: Option
Explanation:
| (A's 1 day's work) : (B's 1 day's work) = | 7 | : 1 = 7 : 4. |
| 4 |
Let A's and B's 1 day's work be 7x and 4x respectively.
| Then, 7x + 4x = | 1 |  11x = |
1 | x = |
1 | . |
| 7 | 7 | 77 |
 A's 1 day's work = |
 |
1 | x 7 |  |
= | 1 | . |
| 77 | 11 |
Discussion:
54 comments Page 6 of 6.
Vembarasi pandiyan said:
1 decade ago
Here efficiency is given so we have to change efficiency into time but in this this why the efficiency is not change I want to know the reason please explain it. 7/4:1=7x:4x this is efficiency 4x:7x this is the time in this question why we are not change the efficiency into time.
Govinda said:
1 decade ago
Why 7/4 explain guys?
Krishna mohan said:
1 decade ago
Given, A+B = 1/7 ------(1).
And A = 7/4B (A is 13/4 times as efficient as B).
Sub A = 7/4B in (1).
We get B = 4/77---- (2).
Then Sub (2) in (1).
We get A = 1/11 (which means A can complete work in 11 days).
And A = 7/4B (A is 13/4 times as efficient as B).
Sub A = 7/4B in (1).
We get B = 4/77---- (2).
Then Sub (2) in (1).
We get A = 1/11 (which means A can complete work in 11 days).
Akhilesh singh(Gwalior) said:
2 decades ago
(a+b)'s one day work=1/7
and a:b::7/4:1
so a/b=7/4
so b=4a/7
substituting the value to above eq'n
(a+4a/7)=1/7
11a/7=1/7
a=1/11 answer.
and a:b::7/4:1
so a/b=7/4
so b=4a/7
substituting the value to above eq'n
(a+4a/7)=1/7
11a/7=1/7
a=1/11 answer.
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