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 18 of 36.

Varun said:   1 decade ago
How you can take total working days as 3 in last step?

Narendra patidar said:   1 decade ago
Please clear explain.

Manisha said:   1 decade ago
Please tell me answer in LCM method.

Lakhan said:   1 decade ago
Why 3 is multiplied by 5 in first method?

Mareeswari said:   10 years ago
Sir I can't understand the A is working two days please explain.

Manju verma said:   10 years ago
Thank you for the solution its really easy way to understand.

Jibinlal said:   10 years ago
1/5 work is done in 3 days. Remaining work is 4/5.

1/5+1/5+1/5+1/5 = 3+3+3+3 = 12 days.

Total = 12 days (4/5th work)+3 days (1/5th work). So 15 days.

Tarun said:   10 years ago
Anyone explain this question with LCM method.

Manju said:   10 years ago
LCM OF 20, 30, 60 is 60. Work out LCM method that means 10*2*3=60.

Abhishek said:   10 years ago
Let A does work in x days.

Let B does work in y days.

y - x = 60.

3x = y.
3x-x = 60.

x = 30.
y = 90.

Hence, both will do work in (1/30+1/90) = 6/135.

No of days = 135/6.

22.5 = 45/2.

Answer = 22.1/2.


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