Aptitude - Time and Work - Discussion
Discussion Forum : Time and Work - General Questions (Q.No. 4)
4.
A is thrice as good as workman as B and therefore is able to finish a job in 60 days less than B. Working together, they can do it in:
Answer: Option
Explanation:
Ratio of times taken by A and B = 1 : 3.
The time difference is (3 - 1) 2 days while B take 3 days and A takes 1 day.
If difference of time is 2 days, B takes 3 days.
| If difference of time is 60 days, B takes |  |
3 | x 60 |  |
= 90 days. |
| 2 |
So, A takes 30 days to do the work.
| A's 1 day's work = | 1 |
| 30 |
| B's 1 day's work = | 1 |
| 90 |
| (A + B)'s 1 day's work = | |
1 | + | 1 | |
= | 4 | = | 2 |
| 30 | 90 | 90 | 45 |
 A and B together can do the work in |
45 | = 22 | 1 | days. |
| 2 | 2 |
Discussion:
284 comments Page 8 of 29.
@verma ji said:
9 years ago
Hello Friends: this shortcut formula is better to solve these type question in less time.
Alternate Method: Since 'A' is 'm' times as efficient as 'B' & takes 'D' days less than 'B', then the time required to complete the job together is given by,
T = m * D/(m^2 " 1)
T = 3 * 60 / [(3)^2 - 1] = 180 / 8 = 22 1/2 days.
Alternate Method: Since 'A' is 'm' times as efficient as 'B' & takes 'D' days less than 'B', then the time required to complete the job together is given by,
T = m * D/(m^2 " 1)
T = 3 * 60 / [(3)^2 - 1] = 180 / 8 = 22 1/2 days.
Thirupathi Malavath said:
1 decade ago
Simple method:
Say B completes the work in 'x' days.
Then A will take (x-60) days to finish the work.
Since A is thrice as good as B, 3A=B.
Therefore, 3 (x-60) =x, x=90.
B's 1 day work=1/90, A's 1 day work=1/30.
(A+B) 's 1 day work= (1/90+ 1/30) =2/45.
Therefore, both can finish the work in 45/2 days i.e., 22 1/2.
Say B completes the work in 'x' days.
Then A will take (x-60) days to finish the work.
Since A is thrice as good as B, 3A=B.
Therefore, 3 (x-60) =x, x=90.
B's 1 day work=1/90, A's 1 day work=1/30.
(A+B) 's 1 day work= (1/90+ 1/30) =2/45.
Therefore, both can finish the work in 45/2 days i.e., 22 1/2.
Malleswari said:
1 decade ago
A is thrice as good as B means 3A = B.
A finish the work 60 days less than B means A = B-60.
So, 3(B-60) = B.
3B-180=B.
2B=180.
B=90.
Then,
3A=B.
3A=90.
A=30.
So, A's I day work is 1/30.
B one day work is 1/90.
Then (A+B) 1 day work together is (1/30+1/90) = 2/45.
Total days they work together is. 45/2 = 22.5.
A finish the work 60 days less than B means A = B-60.
So, 3(B-60) = B.
3B-180=B.
2B=180.
B=90.
Then,
3A=B.
3A=90.
A=30.
So, A's I day work is 1/30.
B one day work is 1/90.
Then (A+B) 1 day work together is (1/30+1/90) = 2/45.
Total days they work together is. 45/2 = 22.5.
Sachin said:
1 decade ago
Its very simple.
Suppose B's done work = X day.
Then A's done work = (X-60) day.
Efficiency ratio is.
A : B = 1:3.
(X-60) : (X) = 1:3.
X = 90.
So A's take days = 30.
B's take day = 90.
A's 1 day work = 1/30.
B's 1 day work = 1/90.
(A+B) s 1day work = 1/30 + 1/90 = 2/45.
So together they will take = 45/2.
Suppose B's done work = X day.
Then A's done work = (X-60) day.
Efficiency ratio is.
A : B = 1:3.
(X-60) : (X) = 1:3.
X = 90.
So A's take days = 30.
B's take day = 90.
A's 1 day work = 1/30.
B's 1 day work = 1/90.
(A+B) s 1day work = 1/30 + 1/90 = 2/45.
So together they will take = 45/2.
Pankaj said:
1 decade ago
Let A takes x days to do the work alone
Therefore days taken by b is (x+60).
Now A is 3 times faster than B
So no.of days taken by A will be 3 times less than B.
So
3*x=(x+60)
2x=60
x=30 days //work done by A
Work done by B=30+60=90 days.
Now we can find work done together
1/30 +1/90 to get the answer.
Therefore days taken by b is (x+60).
Now A is 3 times faster than B
So no.of days taken by A will be 3 times less than B.
So
3*x=(x+60)
2x=60
x=30 days //work done by A
Work done by B=30+60=90 days.
Now we can find work done together
1/30 +1/90 to get the answer.
Furquan Shiekh said:
1 year ago
Suppose A takes x days to complete the work.
Therefore, B will take 3x days.
Now, x = 3x- 60.
x= 30 days.
Thus A takes 30 days and B takes 90 days.
Therefore work done by both in 1 day will be (1/30 + 1/90) = 4/90.
Therefore they take (90/4) = 22.5 days to complete the work.
Therefore, B will take 3x days.
Now, x = 3x- 60.
x= 30 days.
Thus A takes 30 days and B takes 90 days.
Therefore work done by both in 1 day will be (1/30 + 1/90) = 4/90.
Therefore they take (90/4) = 22.5 days to complete the work.
(76)
Mancy said:
1 decade ago
Hi @Michael,
By taking the L.C.M of 30 & 90 you'll get 90.
Now, here the value become.
=1/30+1/90.
=(3+1)/90.
=4/90.
=2/45.
So, 2/45 is total work done by them,
But we've to find the days.
By formula work to days.
N work = 1/N days.
So, 2/45 = 45/2 days.
Answer = 22.5days.
By taking the L.C.M of 30 & 90 you'll get 90.
Now, here the value become.
=1/30+1/90.
=(3+1)/90.
=4/90.
=2/45.
So, 2/45 is total work done by them,
But we've to find the days.
By formula work to days.
N work = 1/N days.
So, 2/45 = 45/2 days.
Answer = 22.5days.
JPV said:
9 years ago
Ratio of no days taken to do work by and b= x : 3x.
It's give that diff= 60.
ie 3x-x = 60,
ie x = 30.
No of days taken by B=90.
No of days taken by A=30.
ie total no of days taken when work is done together= 1/30 +1/60,
= 22 1/2.
It's give that diff= 60.
ie 3x-x = 60,
ie x = 30.
No of days taken by B=90.
No of days taken by A=30.
ie total no of days taken when work is done together= 1/30 +1/60,
= 22 1/2.
Mishra said:
3 months ago
Given: A takes 60 days less than B.
So, let A takes 90days,
B takes 30days.
LCM of 90, 30 = 180 and effeciency of A = 2 (180/90), B = 6 (180/30);
Both work together A + B = (2+6) = 8;
So, total work = 180(LCM);
total days = work/efficiency of both.
= 180/8 = 22.5.
So, let A takes 90days,
B takes 30days.
LCM of 90, 30 = 180 and effeciency of A = 2 (180/90), B = 6 (180/30);
Both work together A + B = (2+6) = 8;
So, total work = 180(LCM);
total days = work/efficiency of both.
= 180/8 = 22.5.
(8)
Guarav said:
10 years ago
A is thrice as good as B
i.e A:B = 3:1.
The ratio will be same.
Now let a number of days for B be x.
Thus, for A it becomes (x - 60)
Now equate 3/1 = x/(x-60)(ratio of days of B to the days of A).
3x - 180 = x.
x = 180/3.
x = 90.
No of days by B is 90.
Hence days of A will be 30.
i.e A:B = 3:1.
The ratio will be same.
Now let a number of days for B be x.
Thus, for A it becomes (x - 60)
Now equate 3/1 = x/(x-60)(ratio of days of B to the days of A).
3x - 180 = x.
x = 180/3.
x = 90.
No of days by B is 90.
Hence days of A will be 30.
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers