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:
53 comments Page 3 of 6.
Faisal said:
8 years ago
(A+B)'s 1 day = 1/7
And given that,
B=(4/7)A.
(A+ (4/7)A) 1 day = 1/7
(11/7) A 1 day = 1/7
11 A 1 day= 1
A's 1 day= 1/11.
Therefore, A needs 11 days alone to complete the required work.
And given that,
B=(4/7)A.
(A+ (4/7)A) 1 day = 1/7
(11/7) A 1 day = 1/7
11 A 1 day= 1
A's 1 day= 1/11.
Therefore, A needs 11 days alone to complete the required work.
(4)
Pradeep Oram said:
1 decade ago
Given: A+B = 1/7......(1).
And A = 7/4B (efficient than B).
Put in(1). We get.
B=4/77(work of B).
Then,
Work of A = (1/7)-(4/77) = 7/77 = 1/11 (from eq.(1)).
So, A finish job in 11 days.
And A = 7/4B (efficient than B).
Put in(1). We get.
B=4/77(work of B).
Then,
Work of A = (1/7)-(4/77) = 7/77 = 1/11 (from eq.(1)).
So, A finish job in 11 days.
Kuntal said:
10 years ago
a : b if work ratio is 7 : 4 then time ratio is 4 : 7.
Let a takes 4x and b takes 7x days.
So 1 days total work 1/4x + 1/7x = 1/7.
So here we get x = 11/4.
So a takes 4x = 4*11/4 = 11 days.
Let a takes 4x and b takes 7x days.
So 1 days total work 1/4x + 1/7x = 1/7.
So here we get x = 11/4.
So a takes 4x = 4*11/4 = 11 days.
(1)
SHIVAM RANA said:
1 decade ago
As A = 7/4B-------(1).
=> A+B GIVES WORK DONE IN 7 DAYS.
=> Unity gives that work in 7*(A+B) DAYS.
=> Using (1).
=> A gives that work in (7*(A+4/7A))/A DAYS.
=> 11 DAYS.
=> A+B GIVES WORK DONE IN 7 DAYS.
=> Unity gives that work in 7*(A+B) DAYS.
=> Using (1).
=> A gives that work in (7*(A+4/7A))/A DAYS.
=> 11 DAYS.
Vams'trick said:
8 years ago
B complete work in days = X.
A take days = 4X/7,
A+B work in 1 day = 7/4X + 1/X,
But from problem it is 1/7,
7/4X + 1/X = 1/7,
X =77/4 = B,
A = 4X/7= 4/7 * 77/4 = 11.
A take days = 4X/7,
A+B work in 1 day = 7/4X + 1/X,
But from problem it is 1/7,
7/4X + 1/X = 1/7,
X =77/4 = B,
A = 4X/7= 4/7 * 77/4 = 11.
(1)
Sm Jahid said:
9 years ago
Let,
A do the job = X day.
and B do the job = 7X/4.
By the question,
1/X+4/7X = 1/7,
=> 7+4/7X = 1/7,
=> 7X = 77,
=> X = 11.
So A do the job in 11 days.
A do the job = X day.
and B do the job = 7X/4.
By the question,
1/X+4/7X = 1/7,
=> 7+4/7X = 1/7,
=> 7X = 77,
=> X = 11.
So A do the job in 11 days.
(1)
Pari said:
1 decade ago
GIVEN : A=7/4B, THEREFORE B = 4/7A.
A + B = 1/7.
A + 4/7A = 1/7.
11/7A = 1/7.
A = I/7*7/11 = 1/11.
Hence 11 days.
Hope this is a correct way.
A + B = 1/7.
A + 4/7A = 1/7.
11/7A = 1/7.
A = I/7*7/11 = 1/11.
Hence 11 days.
Hope this is a correct way.
Akhilesh singh(Gwalior) said:
1 decade 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.
Jimmy John said:
1 decade ago
A+B=1/7
7A+7B=1-----1
A=7/4B
4A=7B-----2
sub 2 in 1
7A+4A=1 (Since 7B=4A)
therefore 11A=1
A=1/11
therefore A can finish in 11 days
7A+7B=1-----1
A=7/4B
4A=7B-----2
sub 2 in 1
7A+4A=1 (Since 7B=4A)
therefore 11A=1
A=1/11
therefore A can finish in 11 days
(1)
D JOHN said:
1 decade ago
A and B can do a work in 28 days. A is 7/4 efficient than B. If B done the work in how many days. Please explain friends.
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