Aptitude - Time and Work - Discussion

Friends, don't make it complex: Here we go.

Ratio of time taken by A & B = 1:3

And A takes 60 days less then B

Suppose, days taken by B = x then days taken by A = (x - 60)

Thus,

A : B = (x - 60) : x
1 : 3 = (x - 60) : x
1/3 = (x - 60) / x
X = 3 (x - 60)
X = 3x - 180
180 = 3x - x
180 = 2x
X = 180 / 2 = 90

Hence,
Days taken by B = x = 90 days
Days taken by A = (x - 60) = 90 - 60 = 30 days

1 day work of A and B = 1/30 + 1/90
= 4/90
= 2/45

So,
Total days taken by A & B to complete the work = 45/2 = 22.5 days

If difference of time 2 days B takes 3 days

Similarly why don't we take difference of time 60 days B takes 60*3 is 180 days. Please explain to me ?

#include<stdio.h>
void main()
{
float a,b;
int c,d;
printf("enter ratio of A : B\n");
scanf("%f",&a);
printf("enter no of days lesser than B by A to complete work\n");
scanf("%f",&b);
c=ab/(a-1);
d=c-b;
printf("no of days to complete work by A and B is %d",(c*d)/(c+d));
}

Let the time taken by A be x days,
then time taken by B will be 3x days.
Given that,
time taken by A to finish the work = time taken by B -60
i.e, x=3x-60
=> x=30.
Therefore, time taken by A to finish the work is 30 days.
so B takes 90 days.
Now ,work done by A & B in 1 day=1/30 + 1/90
=4/90
=2/45
Time taken by A & B to complete the work=45/2 days
=22 1/2 days

Can you please solve this using unitary method. Its b'coz I follow that method.

A is thrice as good as workman as B means 1:3(Ratio)
Therefore A is able to finish a job in 60 days less than B
So A= 1/60 and B=1/60 .....(Given)
According to the ratio
A=1/60 B=1/3*60 (As we are calculating by days)
So Now A = 1/60 < B = 1/90 (A finishes work less than B)
Working together, they can do it in:
1/A+B = 1/60 + 1/90 (As we are calculating by days))
1/A+B = 2/45
So
A+B = 45/2 Days
Option (B) is the correct ans

B takes 3 times more days than A.

i.e. B=3A.

So. B-A=60.

3A-A=60 =>.

A=30.

B=90.

Now calculate 1 day work of A and B.

Let B do the work in 'x' days.

So, A will take (x-60) days.

Now, ratio of A:B=1:3 (given in ques).

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

=> x=90 (B's 1 day work).

So, A's work=30 days.

Working together=1/30+1/90.

=45/2 days.

Easy and simple.

Very simple way.
3A=1B
B takes x days.
3 (x-60) =x
3x-x=180
X dats is B=90, A=30.
Now,
1/90+1/30=22. 5.

Naveen kumar your explanation is beautiful for me.