Aptitude - Time and Work - Discussion

A is thrice good as B.

So, ratio of work done is 3:1 and A taken 60 days less as compare to B.

Let time taken by B is x so time taken by A is x-60.

So 3:1::x:x-60.

3x-180 = x. So 2x = 180 and x = 90.

Time taken by B = 90 days so time taken By A is 30 days.

A's one day work = 1/30 and B's one day work is 1/90.

Total work done by both A and B in one day = 1/30+1/90.

= 3+1/90 = 4/90 = 2/45 = 22.5 days.

So much confusing answer given. This is basically ratio problem.

60 days less means you have to take ratio of time and solve the problem. A is thrice as better as B means. B takes thrice time compared to A.

i.e Ratio of time taken by A/B = 1/3.

If B takes x days then A takes x-60 days time to complete the work.

i.e Ratio of time taken by A/B = x-60/x.

Therefore 1/3 = x-60/x.

Solve to get x = 90 therefore B takes 90 days and A takes 30 days.

Daily Work of A = 1/30.

Daily Work of B = 1/90.

Adding work of A and B.

Daily work of A and B is 4/90.

So time taken for both A and B to complete the work is 90/4 = 221/2 days!

Simple as that!

We can solve this question easily.

A:B = 1:3.

Difference is 60.

Hence ratio becomes:

A:B = 30:90 = 1:3.

Here we can see diff is 60.

So our answer will be 90*30/90+30 = 270/12.

= 90/4 = 45/2 = 22+1/2.

Time ratio between A and B is 1:3.

A/B = 1/3------ (1).

B takes thrice the time taken by A.

A-B = 60 from A = B+60--- (2).

BY substituting (2) in (1).

Then get time taken by B to finish work in 90 days.

From (1) you get time taken by A to finish work in 30 days.

A's 1 day work is = 1/30.

B's 1 day work is = 1/90.

(A+B) 1 day's work is = (1/30+1/90) = 2/45.

Then time taken by the A and B working together is 45/2.

Can we solve such questions by LCM method? Please help.

A    1x
-- = --- (RATIO OF TIME)
B    3x

And difference is given 60 days.

3x-1x=60.

1x = 30 days for A.
3x = 90 days for B.

I don't remember but I think I have posted the another method up above long time before.

Let A takes x days and B takes y days to complete work. In one day A completed 1/x part of work and B 1/yth.

According to question 1/x = 3*1/y and y-x = 60.

By solving x=30 and y= 90.

So in one day both completed (1/x + 1/y) = 4/90.

They can do it in = 90/4 = 45/2.

1:3.

Total 4 parts.

90/4=22.5 (one part).

Here one part means A's work. Remaining 77.5 belongs to B.

The explanation given above is very difficult to understand please try to explain the concepts as simple as possible.

1:3 = x:(x+60).

1/3 = x/(x+60).

So x+60 = 3x.

60 = 2x.

Then x = 30.