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:
361 comments Page 35 of 37.
Rashmi maurya said:
7 years ago
a b c
20 30 60 (LCM=120)
6 4 2 (a20/120=6, b30/720=4, c60/120=2).
6 + 4 + 2 = 12,
12/120 = 5
5 * 3 = 15.
20 30 60 (LCM=120)
6 4 2 (a20/120=6, b30/720=4, c60/120=2).
6 + 4 + 2 = 12,
12/120 = 5
5 * 3 = 15.
A.Venkatesh Reddy said:
7 years ago
A=20 A Effi=3.
B=30 LCM=60 B Effi=2.
So,Work=60 => 3+3+6=12(3 days work)=> 12*5=60=>15days.
C=60 C Effi=1.
B=30 LCM=60 B Effi=2.
So,Work=60 => 3+3+6=12(3 days work)=> 12*5=60=>15days.
C=60 C Effi=1.
Sivapriya said:
7 years ago
A complete in 20days.
B complete in 30days.
C complete in 60days.
Lcm(20,30,60)= 60.
So total work = 60.
A's one day work = 60/20 = 3.
B's one day work = 60/30 = 2.
C's one day work = 60/60 = 1.
A+B+C 's one day work = 3+2+1=6.
First day A's complete = 3unit of work.
Sec day A complete = 3unit of work.
3rd day A+B+C = 6unit of work.
.
.
So on
First 3day total work completed= 3+3+6=12 unit of work.
So (total work / first schedule work) x schedule days.
= (60/12) x 3.
= 5 x 3 = 15days.
B complete in 30days.
C complete in 60days.
Lcm(20,30,60)= 60.
So total work = 60.
A's one day work = 60/20 = 3.
B's one day work = 60/30 = 2.
C's one day work = 60/60 = 1.
A+B+C 's one day work = 3+2+1=6.
First day A's complete = 3unit of work.
Sec day A complete = 3unit of work.
3rd day A+B+C = 6unit of work.
.
.
So on
First 3day total work completed= 3+3+6=12 unit of work.
So (total work / first schedule work) x schedule days.
= (60/12) x 3.
= 5 x 3 = 15days.
G.prathyusha said:
7 years ago
To complete 1/5th of work - 3 days.
Hence to complete 5/5th of work - x days.
By cross multiply, you will get x value as 15 days.
Hence to complete 5/5th of work - x days.
By cross multiply, you will get x value as 15 days.
Jayshri said:
7 years ago
How got the 3rd step (1/10+1/10)?
Common man said:
7 years ago
3days = 1/5.
6days = 2/5.
9days = 3/5.
12days = 4/5.
15days = 5/5 = 1 total work done is complete.
6days = 2/5.
9days = 3/5.
12days = 4/5.
15days = 5/5 = 1 total work done is complete.
16cs1045 said:
7 years ago
10 %for A in first 2 day 10%(5+3.33+1.66)5 for A in third day and 5 for B and C in third similarly for other 12 day work will complete. Therefore the total time required is 15 day.
Samiksha koli said:
7 years ago
@All.
I couldn't get this. Because A is assisted by B & C on the third day only.
So, A B C will together work for first two days. And for last day A will work alone because he is assisted by B & C for third day. So total work of three days Will be A+B+C=1/10 for 2 days it will be 1/5 and A's last day's work will be 1/20.
So, the total work of three days will be1/4. So total work has to be done in 3*4=12 days.
Correct me, if I am wrong.
I couldn't get this. Because A is assisted by B & C on the third day only.
So, A B C will together work for first two days. And for last day A will work alone because he is assisted by B & C for third day. So total work of three days Will be A+B+C=1/10 for 2 days it will be 1/5 and A's last day's work will be 1/20.
So, the total work of three days will be1/4. So total work has to be done in 3*4=12 days.
Correct me, if I am wrong.
Vivek said:
6 years ago
I can't get 3rd step.
How do 1/10+1/10 came and how it is divided by 5?
How do 1/10+1/10 came and how it is divided by 5?
Sameer said:
6 years ago
Fraction of work done in one by A, B, and C is,
1/20, 1/30 and 1/60.
In first 2 days, fraction of work completed by A is 2/20.
Third day, B and C are assisting A then fraction of work completed on 3rd day will be
1/20 + 1/30+ 1/60 = 6/60 i.e 1/10.
So total fraction of work done after 3 days.
2/20+1/10=4/20 i.e. 1/5.
So complete work will be completed in 5 days.
1/20, 1/30 and 1/60.
In first 2 days, fraction of work completed by A is 2/20.
Third day, B and C are assisting A then fraction of work completed on 3rd day will be
1/20 + 1/30+ 1/60 = 6/60 i.e 1/10.
So total fraction of work done after 3 days.
2/20+1/10=4/20 i.e. 1/5.
So complete work will be completed in 5 days.
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