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:
284 comments Page 13 of 29.

Subhranil Mondal said:   9 months ago
Assume B can do it in x days.
So A can in x/3 days.
x - x/3 = 60.
then x = 90.
So B can do the work in 90 days.
A can do it in 90/3 = 30 days.
A and B together can do it in 90 * 30/90 + 30 = 22.5 (Ans).
(24)

Poor gamer said:   1 decade ago
Let A takes x days and B takes 60+x days.
Its given that A takes 1 days when B takes 3 days.

So,
1/3 = x/x+60.

Cross multiply and we get x = 30 i.e A.
X+60 = 30 + 60 = 90 i.e B.

Remaining as usual.

Kavya said:   1 decade ago
A is twice as good a workmen as B and together they can finish a piece of work in 18days. In how many days will A alone finish the work?

Can we solve the above problem using the formula k*x/k^2-1.

Rajeesh kumar said:   5 years ago
@All.

We can easily convert it to a linear equation.

Let B requires x days and forA it is y
it is given,x = 3y.

In the same way;
X-60=Y
By solving we have 2x- 180=0 :.x=90.
and y=90 - 60 = 30.

Ameer said:   7 years ago
Thank you, excellent explanation.

a = 3b --> (1).

a-b = 60.
3b-b = 60.

2b = 60.
b = 30.
If b = 30 then from 1a = 3 x 30 = 90.

Now,
= 1/30+1/90.
= 3+1/90.

= 4/90 = 2/45.
= 45/2 = 22.5 days.

Jeev said:   7 years ago
3A = B.

If 60 is less than b(then 60 is two times of a)
then A=30,
b = 3 * 30 = 90,
a+b=1/30+1/90,
3*1/90+1/90,
(3+1)/90.

Where 4/90(to get days upside down).
90/4 = 22(1/2) days.

MOSA said:   6 years ago
Let a did this work in X days.
B can do it in 3x days.


X+60=3x.
X=30.

It means A can complete this work in 30 days and B in 90 days;
Capacity of;
A is 3.
B is 4.
A+B= 4.

TIME =90/4.

Ajishwarya said:   2 months ago
A is thrice as good a workman as B:
So, A = 3 B.
Substitute A as 1/60.
1/60*3 = B.
1/180 = B
Working together :
A + B = 1/60 + 1/180.
= 4/180,
= 1/45 = 45 Days.
(10)

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.

Jezan said:   1 decade ago
According to this question if A is x, B will be x+60
1/3=x/x+60
3x=x+60
2x=6
x=30
A+B'S ONE DAY WORK=1/30+1/90=2/45
SO WHOLE WORK S= 45/2( UPSIDE DOWN)
22.5 DAYS.
HOPE ALL LL GET DIS


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