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?
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 25 of 36.
Shruthi said:
9 years ago
Please explain the 2nd step => (A + B + C) 's 1 day's work.
How it becomes 6/60.
How it becomes 6/60.
Jemish said:
9 years ago
My new approach to explaining the answer.
=> A is working continuously.
=> B and C join at every 3rd day.
A's efficiency is used as it is,
But B and C's efficiency is used 1/3rd part considering a task.
thus,
A--> 1/20
B--> 1/3 * (1/30)
c--> 1/3 * (1/60)
Now simple.
To find out days required = 1/20 + 1/90 + 1/180 = 1/15.
Answer: 15 days required.
=> A is working continuously.
=> B and C join at every 3rd day.
A's efficiency is used as it is,
But B and C's efficiency is used 1/3rd part considering a task.
thus,
A--> 1/20
B--> 1/3 * (1/30)
c--> 1/3 * (1/60)
Now simple.
To find out days required = 1/20 + 1/90 + 1/180 = 1/15.
Answer: 15 days required.
Jenni said:
9 years ago
How to multiply and solve this equation?
1/20 + 1/30 + 1/60
1/20 + 1/30 + 1/60
Preethu said:
9 years ago
Why do we multiply it by 5?
How we get the answer as 15? Please help me.
How we get the answer as 15? Please help me.
Aariz said:
9 years ago
Hey, guys. I have some confusion in this question. Is there anyone from Delhi, please guide me to solve this question.
Rayhan said:
9 years ago
Good explanation. I really understand this. Thankyou all.
Praveen said:
9 years ago
(A + B + C) = 1/20 + 1/30 + 1/60.
Given 180/1800.
For 20, 30 & 60 the common multiple is 1800 (LCM).
Then you'll get the sum of 180/1800.
This is how I got 1/10 for the work done by A, B & C in 1 day.
Given 180/1800.
For 20, 30 & 60 the common multiple is 1800 (LCM).
Then you'll get the sum of 180/1800.
This is how I got 1/10 for the work done by A, B & C in 1 day.
Bhavnesh said:
9 years ago
Hi friends.
I just want to know why we are taking 3 days work for 1/10 + 1/10.
I just want to know why we are taking 3 days work for 1/10 + 1/10.
Ismail said:
9 years ago
Why didn't we take first B + C one day work is 1/30 + 1/60 = 1/20?
Please explain me.
Please explain me.
Aaron said:
9 years ago
At the last step 1/5 * 3 we must do reciprocal right?
Or just multiple and get 15 for the sake of the answer in the options. Please tell me.
Or just multiple and get 15 for the sake of the answer in the options. Please tell me.
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