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:
281 comments Page 12 of 29.
Govardhan reddy said:
1 decade ago
Why were their difference between days? Please explain to me.
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.
Raj said:
1 decade ago
Easy lets assume A works total days = X.
So A one day work = 1/X.
B is working 3 times less than A.
So Total days of B is = 3X.
So B Works one day = 1/3X.
Different between total days of B and A is 60.
So 3X-X = 60.
2X = 60.
X = 30.
Now normal maths. Replace X with numbers. You will get answer.
So 1/30-1/90 = 22.5.
So A one day work = 1/X.
B is working 3 times less than A.
So Total days of B is = 3X.
So B Works one day = 1/3X.
Different between total days of B and A is 60.
So 3X-X = 60.
2X = 60.
X = 30.
Now normal maths. Replace X with numbers. You will get answer.
So 1/30-1/90 = 22.5.
Arjun said:
1 decade ago
Can any one give me a easier way using LCM method?
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.
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.
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.
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.
Megala said:
1 decade ago
Please explain last 2 steps.
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.
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