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 17 of 29.
Manju gouda said:
1 decade ago
Let us take B's work days be 'x'.
Then A's will be x/3.
Given difference is 60.
Therefore x-x/3 = 60 on solving x = 90.
Therefore B days = 90 & A = 30.
A&B together will be (90*30)/(90+30) = 22.5 days.
Then A's will be x/3.
Given difference is 60.
Therefore x-x/3 = 60 on solving x = 90.
Therefore B days = 90 & A = 30.
A&B together will be (90*30)/(90+30) = 22.5 days.
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.
Sharad said:
1 decade ago
Given A is thrice as good as B,
Therefore 3:1.
i.e 3x:x (ability to work). (Time taken is inverse of work).
Time taken by A and B to complete work = x:3x.
Difference A-B = 60.
Therefore x-3x = 60.
x = 60/2 = 30.
Now x:3x = 30:3(30).
= 30:90.
(A+B) 's 1 day = (1/30)+(1/90).
1 day = 2/45 work.
45/2 day = 1 work.
22. 5 day = 1 work.
Therefore 3:1.
i.e 3x:x (ability to work). (Time taken is inverse of work).
Time taken by A and B to complete work = x:3x.
Difference A-B = 60.
Therefore x-3x = 60.
x = 60/2 = 30.
Now x:3x = 30:3(30).
= 30:90.
(A+B) 's 1 day = (1/30)+(1/90).
1 day = 2/45 work.
45/2 day = 1 work.
22. 5 day = 1 work.
Surya said:
1 decade ago
Simple formula with solution:
(D) n/n2 (i.e n square)-1 = work together.
Details:
D-60, n-3, by putting the formula = (60)3/3's square-1 = 22.5 days.
(D) n/n2 (i.e n square)-1 = work together.
Details:
D-60, n-3, by putting the formula = (60)3/3's square-1 = 22.5 days.
Megala said:
1 decade ago
Please explain last 2 steps.
Rajat singh said:
1 decade ago
Simple solution:
a = 3b.
a-b = 60 (difference of b).
3b-b = 60.
b = 30, a = 90.
So they can together work in 1/30+1/90 = 4/90.
:->22.50.
a = 3b.
a-b = 60 (difference of b).
3b-b = 60.
b = 30, a = 90.
So they can together work in 1/30+1/90 = 4/90.
:->22.50.
Neeraj said:
1 decade ago
Shortcut:
A & B together will complete in 6/14/8 = 24/7 days = 3 3/7 days.
Work completed in 3 days. So C's share 3/7 days.
Now 3200/24/7*3/7 = 400.
A & B together will complete in 6/14/8 = 24/7 days = 3 3/7 days.
Work completed in 3 days. So C's share 3/7 days.
Now 3200/24/7*3/7 = 400.
Pratyush said:
1 decade ago
Can we do it like this:
a = 3b....(1).
a-b = 60.
3b-b = 60.
2b = 60.
b = 30.
If b = 30 then from 1a = 3x30 = 90.
Now,
= 1/30+1/90.
= 3+1/90.
= 4/90 = 2/45.
= 45/2 = 22.5 days.
a = 3b....(1).
a-b = 60.
3b-b = 60.
2b = 60.
b = 30.
If b = 30 then from 1a = 3x30 = 90.
Now,
= 1/30+1/90.
= 3+1/90.
= 4/90 = 2/45.
= 45/2 = 22.5 days.
Mohit Agnihotri said:
1 decade ago
Work done ratio (A:B) = 3:1.
And let x be no. of days taken by B.
So, A:B = x-60:x {Given- A finish a job in 60 days less than B}.
Now, (x-60)/x = 1/3.
3x-180 = x => x = 90.
It means A takes 30 days and B takes 90days.
One day work of A and B is 1/30+1/90 = 4/90.
Thus, 90/4 = 22.5 days required to complete the work.
And let x be no. of days taken by B.
So, A:B = x-60:x {Given- A finish a job in 60 days less than B}.
Now, (x-60)/x = 1/3.
3x-180 = x => x = 90.
It means A takes 30 days and B takes 90days.
One day work of A and B is 1/30+1/90 = 4/90.
Thus, 90/4 = 22.5 days required to complete the work.
Arjun said:
1 decade ago
Can any one give me a easier way using LCM method?
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