Aptitude - Time and Work - Discussion
Discussion Forum : Time and Work - General Questions (Q.No. 1)
1.
A can do a work in 15 days and B in 20 days. If they work on it together for 4 days, then the fraction of the work that is left is :
Answer: Option
Explanation:
| A's 1 day's work = | 1 | ; |
| 15 |
| B's 1 day's work = | 1 | ; |
| 20 |
| (A + B)'s 1 day's work = |  |
1 | + | 1 |  |
= | 7 | . |
| 15 | 20 | 60 |
| (A + B)'s 4 day's work = | |
7 | x 4 | |
= | 7 | . |
| 60 | 15 |
| Therefore, Remaining work = | |
1 - | 7 | |
= | 8 | . |
| 15 | 15 |
Discussion:
344 comments Page 6 of 35.
Mouni said:
10 years ago
A's days = 15.
B's days = 20.
LCM of both = 60 (total work also).
A's work per day = 60/15 = 4.
B's work per day = 60/20 = 3.
Both can do work in one day = (4+3) = 7.
4 days work of both = 7*4 = 28.
Then remaining work = (60-28) = 32.
So please tell me how can I fractionate it?
B's days = 20.
LCM of both = 60 (total work also).
A's work per day = 60/15 = 4.
B's work per day = 60/20 = 3.
Both can do work in one day = (4+3) = 7.
4 days work of both = 7*4 = 28.
Then remaining work = (60-28) = 32.
So please tell me how can I fractionate it?
Ajay said:
1 decade ago
@Prem.
Always remember that while solving percentage total is 100% and similarly in ratio the total is 1/1 i.e 1.
Example : You can say that total work is done only when ratio comes in form of 1/1 , 2,2, 3,3,...... 50/50 and so on......
Answer will always come in 1/1(i.e total).
Always remember that while solving percentage total is 100% and similarly in ratio the total is 1/1 i.e 1.
Example : You can say that total work is done only when ratio comes in form of 1/1 , 2,2, 3,3,...... 50/50 and so on......
Answer will always come in 1/1(i.e total).
Arafat Neloy said:
10 years ago
A can do a work in 15 days and B in 20 days.
A: 15 days-----1 work.
1 day-------1/15 work.
4 days------4/15 work.
B: 20 days-----1 work.
1 day-------1/20 work.
4 days------4/20 work or 1/5 work.
4/15 + 1/5 = 7/15.
Total work 1.
So, remaining work (1-7/15).
= 8/15 answer.
A: 15 days-----1 work.
1 day-------1/15 work.
4 days------4/15 work.
B: 20 days-----1 work.
1 day-------1/20 work.
4 days------4/20 work or 1/5 work.
4/15 + 1/5 = 7/15.
Total work 1.
So, remaining work (1-7/15).
= 8/15 answer.
Vinitha said:
2 years ago
@all
(1/15+1/20) =7/60.
Solution:
We have to use the mixed fraction method in a simple way using cross multiplication so it becomes (15+20)/300.
The reason for the 300 came we use the denominator direct multiplication (15*20=300)
Then 15+20 = 35,
Divide:35/300.
It becomes 7/60.
(1/15+1/20) =7/60.
Solution:
We have to use the mixed fraction method in a simple way using cross multiplication so it becomes (15+20)/300.
The reason for the 300 came we use the denominator direct multiplication (15*20=300)
Then 15+20 = 35,
Divide:35/300.
It becomes 7/60.
(38)
PRAKASH said:
1 decade ago
For A:-
15 days for 1 job
in 1 day 1/15 (part of the one job)
for B:-
20 days for 1 job
in 1 day 1/20 (part of the one job)
FOR BOTH IN ONE DAY:-
1/15+1/20=7/60
FOR BOTH IN 4 DAYS:-
(7/60)*4=7/15(THEY HAVE DONE)
THE REST PART OF THE JOB IS:-
1-(7/15)=8/15 (ANS)
15 days for 1 job
in 1 day 1/15 (part of the one job)
for B:-
20 days for 1 job
in 1 day 1/20 (part of the one job)
FOR BOTH IN ONE DAY:-
1/15+1/20=7/60
FOR BOTH IN 4 DAYS:-
(7/60)*4=7/15(THEY HAVE DONE)
THE REST PART OF THE JOB IS:-
1-(7/15)=8/15 (ANS)
(1)
Fuhar choudhury said:
1 decade ago
I don't understand the logic behind solving such problems. Like people can assume anything anywhere I mean in the first problem itself you assumed let the amount of total work be one but why can't we take 2, 3, 4,..1001, etc. This is the reason mental maths eats me up mentally.
Yeswanth said:
5 years ago
A's 1 day's work =1/15.
B's 1 day's work =1/20.
(A + B)'s 1 day's work = (1/15 + 1/20) = 7/60.
(A + B)'s 4 day's work = 4 * (7/60) = 28/60.
In 4 days they complete 28 parts of work out of 60 parts of work.
Rest of work is 32 parts.
:=> 32/60 has to be completed i.e 8/15.
B's 1 day's work =1/20.
(A + B)'s 1 day's work = (1/15 + 1/20) = 7/60.
(A + B)'s 4 day's work = 4 * (7/60) = 28/60.
In 4 days they complete 28 parts of work out of 60 parts of work.
Rest of work is 32 parts.
:=> 32/60 has to be completed i.e 8/15.
Priya said:
7 years ago
A can do work in 15 days=1/15.
B can do work in 20 days=1/20.
both (A+B)=1/15+1/20=20+15/300=35/300=7/60.
(A+B)Work together in 4 days=7/60*4 in this 60 will be cancelled 4 table in 15.
Then; times=>7/15.
The remaining work will be(1-7/15).
=>15-7/15.
=>8/15.
B can do work in 20 days=1/20.
both (A+B)=1/15+1/20=20+15/300=35/300=7/60.
(A+B)Work together in 4 days=7/60*4 in this 60 will be cancelled 4 table in 15.
Then; times=>7/15.
The remaining work will be(1-7/15).
=>15-7/15.
=>8/15.
Mangesh said:
1 decade ago
When they not mention the quantity of work in problem in that case assume work done is 1. For e.g A can manufacture 1 chair in 15 days while B takes 20 days to manufacture 1 chair in this work done is only 1 that is to manufacture a chair but days require is different.
Sandeep said:
2 years ago
A's 1 day's work = 1/15;
B's 1 day's work = 1/20;
(A + B)'s 1 day's work = (1/15+1/20)= 7/60;
Total days required to complete total work of (A+B) = 60/7,
After 4 days, remaining days left = 60/7 - 4 = 32/7,
Hence, remaining work = 32/7 x 7/60 = 8/15,
Hope it helps.
B's 1 day's work = 1/20;
(A + B)'s 1 day's work = (1/15+1/20)= 7/60;
Total days required to complete total work of (A+B) = 60/7,
After 4 days, remaining days left = 60/7 - 4 = 32/7,
Hence, remaining work = 32/7 x 7/60 = 8/15,
Hope it helps.
(63)
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