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 18 of 36.
Arun said:
1 decade ago
How to make first step?
Sudha said:
1 decade ago
Is there any other simple trick to solve this?
Vishal grade said:
1 decade ago
A's 1 day work = 5%.
B's 1 day work = 3.33%.
C's 1 day work = 1.66%.
A, B and C' 1 day work = 5+3.3+1.6 = 10%.
On 1st 2 days total work = 5+5 = 10%.
On 3rd day total work(by all 3)=10%.
In 3 day total work done=10+10=20%.
20% work done in ---- 3 days.
100% work done in --- 15 days.
B's 1 day work = 3.33%.
C's 1 day work = 1.66%.
A, B and C' 1 day work = 5+3.3+1.6 = 10%.
On 1st 2 days total work = 5+5 = 10%.
On 3rd day total work(by all 3)=10%.
In 3 day total work done=10+10=20%.
20% work done in ---- 3 days.
100% work done in --- 15 days.
Divyanshu Dwivedi said:
1 decade ago
It is much easier by this method :
1/20 + 1/(30*3) + 1/(60*3) = 1/x.
1/20 + 1/90 + 1/180 = 1/x.
12/180 = 1/x.
x = 15 Ans.
1/20 + 1/(30*3) + 1/(60*3) = 1/x.
1/20 + 1/90 + 1/180 = 1/x.
12/180 = 1/x.
x = 15 Ans.
Psyco said:
1 decade ago
1/5th work done in 3 days.
5/5th of work will be done in x days so,
1/5---3.
5/5---x.
x=3*5*5/5.
x=15.
5/5th of work will be done in x days so,
1/5---3.
5/5---x.
x=3*5*5/5.
x=15.
Golu said:
1 decade ago
Why we are calculating 2 days of work A?
Chitra said:
1 decade ago
Work done in 3 days = 1/5.
Work done in next 3 days = 1/5+1/5.
Work done in 5 days = 1/5+1/5+1/5+1/5+1/5 = 5/5 = 1 (task completed).
Hence 3*5 is used.
Work done in next 3 days = 1/5+1/5.
Work done in 5 days = 1/5+1/5+1/5+1/5+1/5 = 5/5 = 1 (task completed).
Hence 3*5 is used.
Mir sakib said:
1 decade ago
What is its mean every third day?
Ajit said:
1 decade ago
Why multiply 1/20*2?
Vijay said:
1 decade ago
B and C joined with A for every 3 days.
So their (A,B,C) 3 days work is == (A's 2 days work i.e. [1/10]) + (A+B+C 's 1 day work i.e [1/10]).
= 1/10+1/10 = 1/5.
So for 3 days 1/5 work is done.
So total work will complete in 15 days.
So their (A,B,C) 3 days work is == (A's 2 days work i.e. [1/10]) + (A+B+C 's 1 day work i.e [1/10]).
= 1/10+1/10 = 1/5.
So for 3 days 1/5 work is done.
So total work will complete in 15 days.
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