Aptitude - Time and Work - Discussion

@All (Must read if you have any doubts)

If B takes 3 days then A takes 1 day to complete the task.

Time taken Ratio => A : B = 1 day : 3 days.

1 3 (difference is 2)

10 30 (diff 20)

30 90 (diff 60) <= Here diff is 60 days, So this is the correct ratio to be used in calculation, since it was mentioned in the given question.

A alone can finish the task in 30 days.
B alone can finish the task in 90 days.

Work done by A alone in 1 day = 1/30
Work done by B alone in 1 day = 1/90

Work done by A and B in one day (1/30 + 1/90) = 3+1/90 = 4/90

The no. of days required to complete the task by A and B is
= 90/4
= 22.5 days.

////**** Important Note: ****////

We cannot take other ratios like 1:3, 10:30, 40:120, 60:180 for the calculation. Since the diff is mentioned as 60 days.

Because, it will give different answers for each different ratios used for calculation.

If we take 1:3 => (1/1 + 1/3) = 4/3

If we take 10:30 => (1/10 + 1/30) = 4/30

If we take 40:120 = (1/40 + 1/120) = 4/120

If we take 60:180 => (1/60 + 1/180) = 4/180 ... so on.

I hope this will help you. Have a nice day!

@Jaswinder singh: I understood your explanation man. Thanks.

Ratio of times taken by A and B = 1 : 3. or 1x:3x
so, we say
3x-1x=60,
2x=60,
x=30, so A will 30 day to complected a work,
B will be complete the work ie 3x, 3(30)=90days,
(A+B) 1 Day work = (1/30 + 1/90)
by solving we get,
A+B 1 Day work = 2/45,
so A and B together can complete work in 45/2 Days.

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

Hey Siva your way of solving is fantastic and understandable! Thanks.

Hi friends, Here is a simple technique to calculate the above problem....

Given,

If the If difference of time is 2 days, B takes 3 days.
If difference of time is 60 days, B takes......?

We can represent the above relation like this,

2------->3
60------>....?

By cross multiplying the above terms we will get... 60*3/2 = 90.

Note:- Always individual term should come in the denominator.

By applying the above procedure you can solve any problem of this type....

I think this technique will help you while doing with this type of problems...

Hai sheetal your shortcut method helps lot to understand so quickly its really super.

Hi Guys,
I think following simple method (alternate) will make you more clear,

A can complete work in N days => A's 1day work = (1/N)----1
B can complete work in n days => B's 1day work = (1/n)----2

Given data,
A thrice as B so , A=3B
A complete work 60 days less than B so, (N=n-60)

Apply in 1 & 2

A's 1day work = (1/(n-60))-----3
B's 1day work = (1/n)--------4

we know that A=3B ; B=(1/n) so,Apply B in A we get[A=3/n]

Apply in 3

3/n=(1/(n-60))
by solving,
3n-180=n
n=90
so, B can complete work in 90 Days => B's 1 Day work =(1/90)
we know that N=n-60,
so, A can complete work in 30 Days => A's 1 Day work = (1/30)

(A+B) 1 Day work = (1/30 + 1/90)
by solving we get,
A+B 1 Day work = 2/45,
so A and B together can complete work in 45/2 Days.

Showry's explanation is good.

SIMPLE AND NICE EXPLANATION!... @KUMAR