Aptitude - Time and Work - Discussion

Discussion Forum : Time and Work - General Questions (Q.No. 3)
3.
A, B and C can do a piece of work in 20, 30 and 60 days respectively. In how many days can A do the work if he is assisted by B and C on every third day?
12 days
15 days
16 days
18 days
Answer: Option
Explanation:

A's 2 day's work = 1 x 2 = 1 .
20 10

(A + B + C)'s 1 day's work = 1 + 1 +1 = 6 = 1 .
20 30 60 60 10

Work done in 3 days = 1 + 1 = 1 .
10 10 5

Now, 1 work is done in 3 days.
5

Whole work will be done in (3 x 5) = 15 days.

Discussion:
357 comments Page 28 of 36.

Subash patra said:   8 years ago
Take whole work is 1.B and C assists A only 3rd day.
So A"s two day work is 1/10.
On 3rd day total work is done is 1/5.

That means 1/5 work done taken in 3rd day. So whole work(1) is done in 15 days.

Lkesh R said:   8 years ago
For whole work take lcm of 20,30 and 60 ie 60 so whole work is 60.
A alone work = 60/20 = 3w/d.
B=2w/d.
C=1w/d.
A+b+c= 6w/d.
A work 3 /day so 60/3=10 days.
It means A alone work 10 days and ie,
10*3(A per day work)= 30.
Remaining work 60-30=30.
So remaining 30 work done by;
A+B+C= 30/6(pr day work)= 5 days,
So total days 10(alone A)+ 5(A+B+C)=15 days.

JPV said:   8 years ago
Hi, I'm not getting the below logic in quotes

" Complete 3 days work is 1/10 + 1/10 = 2/10 =1/5"

Shouldn't that be [ (A's ist day)+ (A's 2nd day) + (A+B+C combined on 3rd day)]?

ie = 1/20 + 1/10 + 1/10?

Please correct me if I am wrong.

JPV said:   8 years ago
Works that done till 3rd day:

[ (A's ist day)+ (A's 2nd day) + (A+B+C combined on 3rd day)].

ie = 1/20+1/10+1/10,
= 1/4.

ie remaining pending work = 3/4.

So, the no of days Al required to complete the work= 20*(3/4),
= 15 days.

Akash kumar said:   8 years ago
Here 3'day's work is 1/5 so next 3 day work is also 1/5.

1/5+ 1/5+ 1/5+ 1/5+ 1/5 i.e its happen 5 times so 3x5= 15 days.

Amit yadav said:   8 years ago
Explain the Step 1.

A's 2 day's work = 1/20*2= 1/10. Explain it clearly.

Shubham said:   8 years ago
Please explain the last step ( 1/10 + 1/10) = 1/5.

Abhishek Rajput said:   8 years ago
solve :: x * (1/20)+x/3*(1/30+1/60) = 1 for x, where x is number of days A worked.

Please, anyone solve this.

Bhaskar I said:   8 years ago
A - 20.
B - 30.
C - 60.
Total work is 60.
Because LCM of ( 20,30,60 ) is 60.
Then A one day work is 60/20 = 3,
B one day work is. 60/30 = 2,
C one day work is 60 /60 = 1,

1st day work is only A = 3.
2nd day work is only A =3.
3rd day work is A+B+C (3+2+1) = 6.

So.,
3 day work 12.
6 day work 24.
9 day work 36.
12 day work 48.
15 day work 60.
Total 60 work is completed in 15 day.
It's simply

Bhuvana said:   8 years ago
It is solved by chocholate method
20 30 60 lcm of those 60.
3 2 1 are their 1 day works.
a a a+b+c a a a+b+c a a a+b+c a a a+b+c a a
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
3 +3 + 7 +3 +3 +7 +3 +3 +7 +3 +3 +7 +3 +3 +7=60 days.


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