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:
20 days
22 1 days
2
25 days
30 days
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 23 of 29.

Sindhu said:   1 decade ago
HI,
This method I feel to be quiet easier.
A is thrice as good as workman as B.
therfore,
A=3B -(1)
finish a job in 60 days less than B
1/B=60+1/A -(2)
i.e B`s One day work = A`s one day work + 60 days.
Solve (1) & (2)
we will get
A= 90;
From (1)
B=A/3
=> B= 30.

(A+B)`s 1 day work = 1/90+1/30
=2/45
=22 1/2 days

Shro said:   1 decade ago
Indhu very easy simple explanation as per the question.
Good :) thanku :)

Kapil said:   1 decade ago
Nic Explanation. . .Sheethal. . .

TABISH said:   1 decade ago
@sheetal
do not able to understand how you get that formula to calculate the time i.e.
K*X/K^2-1

Raman(UIET,KUK) said:   1 decade ago
Guys check this out and don't be confused....
as we know A is 3 time better than B and A takes 60 days less than B so, time taken by A: time taken by B= 1:3
= b-60:b ( suppose time by B is b)
by cross multiply, 3b-180=b
i.e. b=90 so time taken by B=90
and time taken by the A is=90-60= 30

Aarush said:   1 decade ago
Thanks sheetal.

Varma said:   1 decade ago
Nice formula @Sheetal.

Sureshkumar said:   1 decade ago
Another easy way 2 find out:

1st put the ratio i.e.1:3(A:B)
2nd the condition given here is A can work less than 60 days

So, find out the probability that matches with the ratio condition(A&B must be difference 60 here) for eg:let we take as A as 20 therefore B must be 60(here we get the difference as 40 only)according to 1:3 which cant satisfy

The given condition(A less than B by 60 days) suppose you take A as 30 means you get B as 90 which is greater than 60 days
of A....A=30 B=90 A's 1 day work=1/30

B's 1 day work=1/90 A+B's 1 day work =1/30+1/90=4/90 here they are not given to find out as 1day work...so take as 90/4=22.5 <==> 22(1/2).

Abhay said:   1 decade ago
@Neeraj-A will finish the work 60 days lesser than B,means if B takes 60 days to complete the work,A takes 1 day.

Neeraj said:   1 decade ago
A will finish the work 60 days lesser than B.

What is it mean please explain?


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