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 32 of 36.

Anil said:   1 decade ago
Thanks benny.

Manoj said:   1 decade ago
i.e;

3 days =1/5

6 days=2/5

9 days=3/5

12 days=4/5

15 days=5/5(1)==work completed
(1)

Harry said:   1 decade ago
1.)days worked by A is 2; 1 day helped by B and C and not A,
2.)given is A's 3 day work
3.)total 1 day work of A,B,C is find
4.)A's 2 day work is found
Result calculation:
A's 3day work=>(1/10)+(1/10)=>A 2day work+A,B,C's 1days)
=>1/5(of whole work) [5 is n]
A's whole work=3*5=15days

Neetu singh said:   1 decade ago
@benny-reli nice explanation.

Preethi said:   1 decade ago
1/5 of work being done in 3 days. But how do we arrive at the total no. Of days worked by A? what is the logic behind?

Sathish said:   1 decade ago
Hi friends,

we know that whole work completed means we will denote it as 1(full)....

2=1(in 2days full work get completed)
5=1(in 5days full work get completed)
just simple 5=1/2 =>5*2=1(just cross multiple the 2)

Benny said:   1 decade ago
Here my simple ans:

A is working continue 2 day's.So he's 2day's work is:1/20*2=1/10;

in 3rd day he join other two person B and C.So here 3 member work:

1/20+1/30+1/60=1/10;

3 day's work is :1/0+1/10=1/5

So total work done by them is 10+5=15;
(1)

Sindhu said:   1 decade ago
@Baskar

Can you please explain me why do you cross multiply at the end for the answer?

Kumar said:   1 decade ago
Can you please tell me how you get 6/60?

Arpit Mathur said:   1 decade ago
Hey please explain why A's 2 day work is taken?


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