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:
283 comments Page 20 of 29.
Soniya said:
9 years ago
Let t1 &t2 are time taken by A and B.
w1 & w2 are work done by A and B.
Ratio of the time taken by A and B =1 : 3.
Then, A = x, B = 3x (x is some constant).
We know that t1 = t2 - 60 (A takes 60 days less than B).
t2 - t1 = 60
3x - x = 60 (t1 = x, t2 = 3x)
x = 30.
Then t1=30 and t2 = 90.
Total work done by A& B(W) = w1 + w2.
W =1/t1 + 1/t2.
= 1/30 + 1/90 = 2/45.
Then time taken by A&B to finish the work is 45/2days.
w1 & w2 are work done by A and B.
Ratio of the time taken by A and B =1 : 3.
Then, A = x, B = 3x (x is some constant).
We know that t1 = t2 - 60 (A takes 60 days less than B).
t2 - t1 = 60
3x - x = 60 (t1 = x, t2 = 3x)
x = 30.
Then t1=30 and t2 = 90.
Total work done by A& B(W) = w1 + w2.
W =1/t1 + 1/t2.
= 1/30 + 1/90 = 2/45.
Then time taken by A&B to finish the work is 45/2days.
Devendra kumar said:
9 years ago
Please tell me the easiest solution of this problem. Like LCM method.
Udhay said:
9 years ago
I can't understand it. Please someone help me.
Dineshkumar said:
9 years ago
Your answer is clear @Sundar, Thanks.
Hari said:
9 years ago
A:B = 3:1 efficiency.
Because, A is Thrice the work as B.
So, A complete the work 60 days before.
Then 2---60
1--30,
So to find total work we just take it as;
A = 3 * 30. B = 1 * 30.
Total work is 90(LCM IS 90).
So, W = ED,
D = 90/4
= 22.5.
Because, A is Thrice the work as B.
So, A complete the work 60 days before.
Then 2---60
1--30,
So to find total work we just take it as;
A = 3 * 30. B = 1 * 30.
Total work is 90(LCM IS 90).
So, W = ED,
D = 90/4
= 22.5.
BLACK said:
9 years ago
Ratio of time taken by A & B = 1 : 3.
Suppose B takes x days to finish the job.
Then A takes (x-60) days.
So, (x-60) : x = 1:3
x= 90.
So rest are same.
Suppose B takes x days to finish the job.
Then A takes (x-60) days.
So, (x-60) : x = 1:3
x= 90.
So rest are same.
@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.
Suresh said:
9 years ago
A is 3 times more efficient than B,
A=3B
A do the work less than 60 days compared to B,
A-60=B.
So, we can write it as,
A = 3(A+60)
A = 3A+180
2A = 180
A = 90
90-60 = B
B = 30.
A=3B
A do the work less than 60 days compared to B,
A-60=B.
So, we can write it as,
A = 3(A+60)
A = 3A+180
2A = 180
A = 90
90-60 = B
B = 30.
Hari. said:
9 years ago
Thanks @Sachin.
JAY said:
9 years ago
LET:
A = 3B.
where:
A = 1/x and B = 1/(x+60)
so;
(1/x) = 3[ 1/(x+60) ]
X = 30.
1/A + 1/B = 1/T
1/30 + 1/(30+60) = 1/T
Then, T = 22.5 answer.
A = 3B.
where:
A = 1/x and B = 1/(x+60)
so;
(1/x) = 3[ 1/(x+60) ]
X = 30.
1/A + 1/B = 1/T
1/30 + 1/(30+60) = 1/T
Then, T = 22.5 answer.
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