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:
359 comments Page 9 of 36.

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

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

Sindhu said:   1 decade ago
@Baskar

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

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)

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?

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

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

Anil said:   1 decade ago
Thanks benny.

Poornima said:   1 decade ago
How can you taking that 3 days? and 1/10+1/10 what is it ?

Imraz said:   1 decade ago
Here 15 days is required for the completion of the work by A, B, C. But in question it is asked 'in how many days can A do the work' - which means the number of days A worked. So to get this we need to divide the 15 by 3 and get '5' as answer.

Can anyone please make me clear if my interpretation is incorrect ?


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