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:
359 comments Page 29 of 36.
Bhaskar I said:
9 years ago
A - 20.
B - 30.
C - 60.
Total work is 60.
Because LCM of ( 20,30,60 ) is 60.
Then A one day work is 60/20 = 3,
B one day work is. 60/30 = 2,
C one day work is 60 /60 = 1,
1st day work is only A = 3.
2nd day work is only A =3.
3rd day work is A+B+C (3+2+1) = 6.
So.,
3 day work 12.
6 day work 24.
9 day work 36.
12 day work 48.
15 day work 60.
Total 60 work is completed in 15 day.
It's simply
B - 30.
C - 60.
Total work is 60.
Because LCM of ( 20,30,60 ) is 60.
Then A one day work is 60/20 = 3,
B one day work is. 60/30 = 2,
C one day work is 60 /60 = 1,
1st day work is only A = 3.
2nd day work is only A =3.
3rd day work is A+B+C (3+2+1) = 6.
So.,
3 day work 12.
6 day work 24.
9 day work 36.
12 day work 48.
15 day work 60.
Total 60 work is completed in 15 day.
It's simply
Bhuvana said:
9 years ago
It is solved by chocholate method
20 30 60 lcm of those 60.
3 2 1 are their 1 day works.
a a a+b+c a a a+b+c a a a+b+c a a a+b+c a a
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
3 +3 + 7 +3 +3 +7 +3 +3 +7 +3 +3 +7 +3 +3 +7=60 days.
20 30 60 lcm of those 60.
3 2 1 are their 1 day works.
a a a+b+c a a a+b+c a a a+b+c a a a+b+c a a
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
3 +3 + 7 +3 +3 +7 +3 +3 +7 +3 +3 +7 +3 +3 +7=60 days.
Yash said:
9 years ago
Why are we multiplying by 5 for whole work? Explain.
Shruthi said:
9 years ago
From the explaination, we got to know that in 3 day's 1/5 of the work completed.
If A's one day's work is 1/20 then he can complete in 20 days. Same way we should find out 1 day work for the above problem.
i.e., If 3 day's work=1/5.
then one day work=(1/5)/3 =>1/15,
=>so 1 day work=1/15 then he can complete in 15 days.
If A's one day's work is 1/20 then he can complete in 20 days. Same way we should find out 1 day work for the above problem.
i.e., If 3 day's work=1/5.
then one day work=(1/5)/3 =>1/15,
=>so 1 day work=1/15 then he can complete in 15 days.
Deepa said:
9 years ago
Can you explain me how it is 1/5 and 3*15? I'm not getting this concept.
Pooja Kulkarni said:
8 years ago
It can be done in an easier way than the given solution:
Let the number of days required = x.
So basically, B will contribute (1/3)rd of its work in 30 days and C will contribute (1/3)rd of its work in 60 days.
Work by A in one day: 1/20.
Work by B in one day: 1/30.
Work by C in one day: 1/60.
So total work can be easily calculated as:
(x/20) + (1/3)*(x/30) + (1/3)*(x/60) = 1.
So, 12x = 180,
And thus x = 15 days.
Let the number of days required = x.
So basically, B will contribute (1/3)rd of its work in 30 days and C will contribute (1/3)rd of its work in 60 days.
Work by A in one day: 1/20.
Work by B in one day: 1/30.
Work by C in one day: 1/60.
So total work can be easily calculated as:
(x/20) + (1/3)*(x/30) + (1/3)*(x/60) = 1.
So, 12x = 180,
And thus x = 15 days.
Surya said:
8 years ago
Usually, we are taking 20 days means 1/20. Then why there finding 2 days work is multiplied by 2?
My thoughts are 1/20*1/2. Please explain me.
My thoughts are 1/20*1/2. Please explain me.
Dhivyabharathi said:
8 years ago
Nice explanation @Nikita.
Veena said:
8 years ago
Why we add 1/10 and 1/10 here? Please explain.
Salman said:
8 years ago
How 6/60 come?
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