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 4 of 6.
Pawan narkhede said:
1 decade ago
How to come A is 7/4 times efficient than B?
Sunil kumar said:
1 decade ago
Efficiency ratio is 7:4.
Time ratio is 4:7.
Work ratio is inversely proportional to time ratio.
Here A is more efficient so A's time is less, B is less efficient than a so B take more time than A.
So both take 28 days (7 + 4) 11 ---- 28.
11/7*28 = 11*4 = 44 days.
So answer is 44 days.
Time ratio is 4:7.
Work ratio is inversely proportional to time ratio.
Here A is more efficient so A's time is less, B is less efficient than a so B take more time than A.
So both take 28 days (7 + 4) 11 ---- 28.
11/7*28 = 11*4 = 44 days.
So answer is 44 days.
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.
Iovd said:
1 decade ago
@Raj.
They given 1*3/4 in example after solving it we get 7/4(4*1+3).
They given 1*3/4 in example after solving it we get 7/4(4*1+3).
Raj said:
1 decade ago
How we get A =7/4? Please help me.
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.
Divi said:
1 decade ago
A is 7/4 efficient than B means A=7/4B =>B=4/7A.
A and B together can complete the work in 7 days.
[i.e.Time is directly proportional to work => 7days=work => 1 day=1/7th work].
So,
A + B = 1/7.
A + 4/7A= 1/7.
11/7A = 1/7.
A = 1/11.
Hence, A alone can work for 11 days.
A and B together can complete the work in 7 days.
[i.e.Time is directly proportional to work => 7days=work => 1 day=1/7th work].
So,
A + B = 1/7.
A + 4/7A= 1/7.
11/7A = 1/7.
A = 1/11.
Hence, A alone can work for 11 days.
Chara said:
1 decade ago
A's working capacity = X.
B's working capacity = Y.
Given, X + Y = 1/30 ................equation(1).
Also, X = 7/4 Y
i.e.. Y= 4/7 X .................equation (2).
PUTTING Y=4/7X from eqtn (2) in Eqtn(1), we get,
X= 1/11.
i.e.. A working capacity is 1/11( interpretation: "A" can do 1 work in 11 days).
B's working capacity = Y.
Given, X + Y = 1/30 ................equation(1).
Also, X = 7/4 Y
i.e.. Y= 4/7 X .................equation (2).
PUTTING Y=4/7X from eqtn (2) in Eqtn(1), we get,
X= 1/11.
i.e.. A working capacity is 1/11( interpretation: "A" can do 1 work in 11 days).
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.
THIVYA said:
1 decade ago
A and B collectively can do the work in 7 days.
so their one day work is 1/7.
A+B = 1/7-------(1).
A is 7/4 times efficient than B which means.
A = (7/4)B ----------(2).
or
B = (4/7)A ------------(2).
Put 2 int 1 eq,
A+(4/7)A = 1/7.
A(11/7) = 1/7.
SO,
A CAN COMPLETE THE PIECE OF WORK IN 11 DAYS.
so their one day work is 1/7.
A+B = 1/7-------(1).
A is 7/4 times efficient than B which means.
A = (7/4)B ----------(2).
or
B = (4/7)A ------------(2).
Put 2 int 1 eq,
A+(4/7)A = 1/7.
A(11/7) = 1/7.
SO,
A CAN COMPLETE THE PIECE OF WORK IN 11 DAYS.
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