Aptitude - Time and Work - Discussion
Discussion Forum : Time and Work - Data Sufficiency 1 (Q.No. 1)
Directions to Solve
Each of the questions given below consists of a statement and / or a question and two statements numbered I and II given below it. You have to decide whether the data provided in the statement(s) is / are sufficient to answer the given question. Read the both statements and
- Give answer (A) if the data in Statement I alone are sufficient to answer the question, while the data in Statement II alone are not sufficient to answer the question.
- Give answer (B) if the data in Statement II alone are sufficient to answer the question, while the data in Statement I alone are not sufficient to answer the question.
- Give answer (C) if the data either in Statement I or in Statement II alone are sufficient to answer the question.
- Give answer (D) if the data even in both Statements I and II together are not sufficient to answer the question.
- Give answer(E) if the data in both Statements I and II together are necessary to answer the question.
1.
A and B together can complete a task in 7 days. B alone can do it in 20 days. What part of the work was carried out by A? | |
I. | A completed the job alone after A and B worked together for 5 days. |
II. | Part of the work done by A could have been done by B and C together in 6 days. |
Answer: Option
Explanation:
| B's 1 day's work = | 1 |
| 20 |
| (A+ B)'s 1 day's work = | 1 |
| 7 |
| I. (A + B)'s 5 day's work = | 5 |
| 7 |
| Remaining work = |  |
1 - | 5 |  |
= | 2 | . |
| 7 | 7 |
 |
2 | work was carried by A. |
| 7 |
II. is irrelevant.
Correct answer is (A).
Discussion:
20 comments Page 1 of 2.
Sunilkumar said:
9 years ago
@Pihu.
A + B's 1day work = 1/7day.
B's 1day work = 1/20 day.
Then,
A + 1/20 = 1/7
After that,
A = 1/7 - 1/20.
by cross multiply,
A = 20 - 7\20 * 7.
A = 13\140.
Then we taking the I in that A completed the job alone after a&b worked together for 5 days.
So, 1st we take a can complete by 5 days.
Then A's 5days work = 13 * 5/140.
then we get 13/28.
Now we want to find A + B's 5days work.
A + B's 1day work = 1/7 day.
Then A + B's 5days work = 5/7 days.
Remaining work = 1 - 5/7 = 2/7 days.
Total part of work by A = 2/7 + 13/28
By taking Lcm = 2 * 4/7 * 4.
Then,
= 8/28 + 13/28 = 8 + 13/28.
After simplification we get,
= 21/28 = 3/4.
A + B's 1day work = 1/7day.
B's 1day work = 1/20 day.
Then,
A + 1/20 = 1/7
After that,
A = 1/7 - 1/20.
by cross multiply,
A = 20 - 7\20 * 7.
A = 13\140.
Then we taking the I in that A completed the job alone after a&b worked together for 5 days.
So, 1st we take a can complete by 5 days.
Then A's 5days work = 13 * 5/140.
then we get 13/28.
Now we want to find A + B's 5days work.
A + B's 1day work = 1/7 day.
Then A + B's 5days work = 5/7 days.
Remaining work = 1 - 5/7 = 2/7 days.
Total part of work by A = 2/7 + 13/28
By taking Lcm = 2 * 4/7 * 4.
Then,
= 8/28 + 13/28 = 8 + 13/28.
After simplification we get,
= 21/28 = 3/4.
(3)
ANKUSH said:
2 decades ago
In this ques no doubt option A is correct, but I guess the explanation given is correct only if it's asked to find out part of work done by A alone.
But ques is wht part of work ws carried out by A(alone + A's contribution when both A & B worked together)which can be calculated as
B's 1 day's work = 1/20
(A+ B)'s 1 day's work = 1/7
=> A's 1 day's work = 1/7 - 1/20 = 13/140
=> A's 5 day's work = 13/28
Now , (A + B)'s 5 day's work = 5/7
Remaining work = 1 - 5/7 = 2/7
=> 2/7 work was carried by A alone
and
Total part of work carried by A = 2/7+13/28= 3/4.
But ques is wht part of work ws carried out by A(alone + A's contribution when both A & B worked together)which can be calculated as
B's 1 day's work = 1/20
(A+ B)'s 1 day's work = 1/7
=> A's 1 day's work = 1/7 - 1/20 = 13/140
=> A's 5 day's work = 13/28
Now , (A + B)'s 5 day's work = 5/7
Remaining work = 1 - 5/7 = 2/7
=> 2/7 work was carried by A alone
and
Total part of work carried by A = 2/7+13/28= 3/4.
(1)
Javeed Ahmed Khan said:
1 decade ago
Easy way of solving this question is:
A and B together can complete a task in 7 days which means
A+B = 7
B alone can do it in 20 days:
B=20
When we substitute B's Value we will get A's Value.
A+20=7
A=(13).
1st statement says that A will complete the task 5 days after A & B worked together, which is acceptable statement.
A and B together can complete a task in 7 days which means
A+B = 7
B alone can do it in 20 days:
B=20
When we substitute B's Value we will get A's Value.
A+20=7
A=(13).
1st statement says that A will complete the task 5 days after A & B worked together, which is acceptable statement.
(1)
Shubham Nale said:
5 years ago
A+B takes 7 days to complete the whole work.
B takes 20 days.
Total work = LCM = 140,
A+B =20 unit/day.
For 5 days =100 unit work is done.
Therefore, 140-100 = 40 unit of work remained.
40/140 =2/7.
B takes 20 days.
Total work = LCM = 140,
A+B =20 unit/day.
For 5 days =100 unit work is done.
Therefore, 140-100 = 40 unit of work remained.
40/140 =2/7.
(1)
Vitthal jadhav said:
9 years ago
B's 1 day's work = 1/20.
(A+ B)'s 1 day's work = 1/7.
=> (A + B)'s 5 day's work = 5/7.
Remaining work = 1 - 5 = 2.7 7
2/7work was carried by A.
(A+ B)'s 1 day's work = 1/7.
=> (A + B)'s 5 day's work = 5/7.
Remaining work = 1 - 5 = 2.7 7
2/7work was carried by A.
Pandurang Mahadev Magar said:
3 years ago
But A also work during the first 5 days why that work is not considered as his part of the work? Anyone, please explain me.
(5)
Nikhitha said:
8 years ago
@Manju.
Firstly given, x/15+5/10=1.
Where we get x/15=1-1/2.
On LCM we get, x/15=1/2.
Now, Cross multiply, 2x=15; x=15/2.
Firstly given, x/15+5/10=1.
Where we get x/15=1-1/2.
On LCM we get, x/15=1/2.
Now, Cross multiply, 2x=15; x=15/2.
Tunna said:
9 years ago
@Ankush.
Can you explain how you got the remaining work = 1 - 5/7 = 2/7 & A's 5days work= 13/28? How you got 28?
Can you explain how you got the remaining work = 1 - 5/7 = 2/7 & A's 5days work= 13/28? How you got 28?
(1)
Keshri said:
5 years ago
It's easily understandable;
A+B=7.
B=20.
After substituting A's efficiency is 13.
So, 1 is agreed.
A+B=7.
B=20.
After substituting A's efficiency is 13.
So, 1 is agreed.
(4)
Srikanth said:
10 years ago
Could someone help me, how shall we get that 2/7 value.
2/7+1/7 results : 21/49 or 3/7 ?
2/7+1/7 results : 21/49 or 3/7 ?
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