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 8 of 29.
Deepti said:
1 decade ago
It is not so big and easy to understand.
let work done by B in 1 day = 1/x
so work done by A in 1 day = 1/(x-60)
1/(x-60) = 3/x
so x = 3x - 180
x = 90
work done by A and B in 1 day is 30 and 90 respectively
work done by both together in 1 day = 1/30 + 1/90 = 2/45.
total work done = 45/2
let work done by B in 1 day = 1/x
so work done by A in 1 day = 1/(x-60)
1/(x-60) = 3/x
so x = 3x - 180
x = 90
work done by A and B in 1 day is 30 and 90 respectively
work done by both together in 1 day = 1/30 + 1/90 = 2/45.
total work done = 45/2
Harsha said:
1 decade ago
Easy method :
A can completed in x days
B can in 3x days then
A = B-60 (A can do in 60 days less than B )
=> x=3x-60 => x= 30 =>
A=30, B=90
Then together work done is (1/30+1/90) = 2/45.
Finally total work done is 45/2.
A can completed in x days
B can in 3x days then
A = B-60 (A can do in 60 days less than B )
=> x=3x-60 => x= 30 =>
A=30, B=90
Then together work done is (1/30+1/90) = 2/45.
Finally total work done is 45/2.
Pinky said:
1 decade ago
@Sheetal superb explanation.
Praveen said:
1 decade ago
Nice exp. Harsha.
Nitin Singla said:
1 decade ago
Hey its simple to understand.
Days taken by B = x
Days taken by A= x - 60
Their time taken proportio is 1:3
so,
x - 60/ x = 1/3
x=90;
So A will do the work in = 30 days
abd B in 3x= 3*30=90 days,
and u can find their 1 day's work and ad it.
Simple :)
Days taken by B = x
Days taken by A= x - 60
Their time taken proportio is 1:3
so,
x - 60/ x = 1/3
x=90;
So A will do the work in = 30 days
abd B in 3x= 3*30=90 days,
and u can find their 1 day's work and ad it.
Simple :)
Srinivas said:
1 decade ago
Hi friends,
Given A:B=1:3
Therefore B=3A--------equation 1
let B can do a work in x days.
then A can do the same work in (x-60) days.
then B=3A
x=(x-60)3
therefore x=90 days
therefore B can do a work in 90 days.
and A will do a work in 90-60=30 days.
Given A:B=1:3
Therefore B=3A--------equation 1
let B can do a work in x days.
then A can do the same work in (x-60) days.
then B=3A
x=(x-60)3
therefore x=90 days
therefore B can do a work in 90 days.
and A will do a work in 90-60=30 days.
Pavethra said:
1 decade ago
I tell that A is thrice as good as B so it should be 3:1 na.
Am I right?
Am I right?
Sunil reddy said:
1 decade ago
We can use a simple formula here:[(KL)/k squqre-1)]
-->here K=3(efficiency),L=60(time) so (3*60/(3*3)-1)=>180/8=221/2
-->here K=3(efficiency),L=60(time) so (3*60/(3*3)-1)=>180/8=221/2
Vinod reddy said:
1 decade ago
THANK U SHEETAL,your short cut method is simply super.there is no words to say
Sundar said:
1 decade ago
If difference of time is 60 days 3*60/2 = 90 days.
I can't get this step?
Please explain.
I can't get this step?
Please explain.
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers