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 1 of 6.
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.
Kirshna said:
1 decade ago
How get a:b :: 7/4:1 ?
Divya said:
1 decade ago
Because a is 7/4 times efficient than b => a= 7/4b
a:b= 7/4b:b (b's get cancelled.)
=> 7/4:1
a:b= 7/4b:b (b's get cancelled.)
=> 7/4:1
M.vignesh said:
1 decade ago
A=7/4
B=1
A:B=7/4:1
So A:b=7:4
Total Working Days=7*4=28
a=28/7=4
b=28/4=7
a=a+b
a=4+7=11
A alone=11
B=1
A:B=7/4:1
So A:b=7:4
Total Working Days=7*4=28
a=28/7=4
b=28/4=7
a=a+b
a=4+7=11
A alone=11
Pankaj said:
1 decade ago
How Total Working Days=7*4=28 ?
UMESH PRASAD 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 then B which means
A=(7/4)B ----------
or
B=(4/7)A ------------(2)
put the value of (2)in (1)
(4/7)*B+B=1/7
B=1/11 THIS IS HIS ONE DAY WORK
ALONE B CAN FINISH IN 11 DAY
so their one day work is 1/7
A+B=1/7-------(1)
A is 7/4 times efficient then B which means
A=(7/4)B ----------
or
B=(4/7)A ------------(2)
put the value of (2)in (1)
(4/7)*B+B=1/7
B=1/11 THIS IS HIS ONE DAY WORK
ALONE B CAN FINISH IN 11 DAY
Nidhi 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 then B which means.
A= (7/4) B.
Or.
B= (4/7) A - (2).
Put the value of (2) in (1).
(4/7) *B+B=1/7.
B=1/11 THIS IS HIS ONE DAY WORK.
ALONE B CAN FINISH IN 11 DAY.
So their one day work is 1/7.
A+B=1/7-- (1).
A is 7/4 times efficient then B which means.
A= (7/4) B.
Or.
B= (4/7) A - (2).
Put the value of (2) in (1).
(4/7) *B+B=1/7.
B=1/11 THIS IS HIS ONE DAY WORK.
ALONE B CAN FINISH IN 11 DAY.
Varun said:
1 decade ago
Ratio type problem solve by 'x' value.
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)
Heena said:
1 decade ago
@nidhi
if A=(7/4)B
then Eq2 should be
7/4(B)+B=1/7
if A=(7/4)B
then Eq2 should be
7/4(B)+B=1/7
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers