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 13 of 29.
M ahmad said:
1 decade ago
A can do the job in x days.
B can same job in 3x days.
3x=x+60 by B.
x=30.
One day work by A and B = 1/30+1/90 = 4/90 = 2/45.
Whole job done by A and B = 45/2 = 22.5 days.
B can same job in 3x days.
3x=x+60 by B.
x=30.
One day work by A and B = 1/30+1/90 = 4/90 = 2/45.
Whole job done by A and B = 45/2 = 22.5 days.
Michael said:
1 decade ago
How do we get 4/90 ?
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.
Sundar said:
1 decade ago
Please Tell me how 3/2 has come?
Atul1487 said:
1 decade ago
What is need to take time difference?
How will I come to know that I need to calculate time difference?
How will I come to know that I need to calculate time difference?
Venkatesh said:
1 decade ago
Hi friends just read, A's works 3 times than B so work ration 3:1 and time ratio will be 1:3 in the question they ask for time so 3/(3-1)*60=90.
A 3 times better 3/90=1/30(1 days work) B 1/90 1days work together 1/90+1/30=answer.
A 3 times better 3/90=1/30(1 days work) B 1/90 1days work together 1/90+1/30=answer.
Kumar said:
1 decade ago
How its "4/90 " ?
Poornachandran said:
1 decade ago
Guys,
I'll tell by simple method.
Given, A is thrice of B.
So A = 3B---->(1).
A's 1 day work is A=1/60--->(2).
Substitute (2) in (1),
A=3B.
We get,
3B=1/60.
B=1/180.
In question they asked A+B=how many working days?
We know A and B values.
Add A and B.
1/60+1/180=1/Work days.
Take L.C.M.
3+1/180=1/Work days.
4/180=1/work days.
1/45=1/work days.
Work days=45.
By fraction we can write 22 1/2 days.
I'll tell by simple method.
Given, A is thrice of B.
So A = 3B---->(1).
A's 1 day work is A=1/60--->(2).
Substitute (2) in (1),
A=3B.
We get,
3B=1/60.
B=1/180.
In question they asked A+B=how many working days?
We know A and B values.
Add A and B.
1/60+1/180=1/Work days.
Take L.C.M.
3+1/180=1/Work days.
4/180=1/work days.
1/45=1/work days.
Work days=45.
By fraction we can write 22 1/2 days.
Nithya said:
1 decade ago
Lets B takes x days to complete the Work,
Then B 's Capacity ==>1/x.
A is 3 times as good as A so A'S capacity is 3/x.
Then Time Taken by B is = x/1.
Time taken by A is = x/3.
Time difference (x-x/3)=60.
Which gives x = 90.
Time taken By B = 90.
Time taken By A = 30.
(A's Work +B's Work) 1 day Work = (1/30)+(1/90).
= 4/90.
Then Time taken to complete work is 90/4 ==> 22.5 days.
Then B 's Capacity ==>1/x.
A is 3 times as good as A so A'S capacity is 3/x.
Then Time Taken by B is = x/1.
Time taken by A is = x/3.
Time difference (x-x/3)=60.
Which gives x = 90.
Time taken By B = 90.
Time taken By A = 30.
(A's Work +B's Work) 1 day Work = (1/30)+(1/90).
= 4/90.
Then Time taken to complete work is 90/4 ==> 22.5 days.
Pranay said:
1 decade ago
The work being done by A & B is in ratio of 1:3.
This means if A does a work in 1 day, than B will do this work in 3 days.
Now let suppose this ratio is multiplied by a factor, say x.
Then ratio becomes x:3x.
Now another relation given is that A can do work 60 days faster then B. Mathematically we can write it as.
x=3x-60.
Solving this, we get x = 30.
Hence the ratio becomes 30:60.
Now we can calculate the time taken by them.
This means if A does a work in 1 day, than B will do this work in 3 days.
Now let suppose this ratio is multiplied by a factor, say x.
Then ratio becomes x:3x.
Now another relation given is that A can do work 60 days faster then B. Mathematically we can write it as.
x=3x-60.
Solving this, we get x = 30.
Hence the ratio becomes 30:60.
Now we can calculate the time taken by them.
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers