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:
21 comments Page 2 of 3.
Sunilkumar said:
10 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)
Pihu said:
1 decade ago
@Ankush.
How you got 28? please explain.
How you got 28? please explain.
Akshay said:
1 decade ago
@Ankush.
Agree with you, even I got the same answer.
Agree with you, even I got the same answer.
Tunna said:
1 decade 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)
Srikanth said:
1 decade 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 ?
Lakshminarayana said:
1 decade ago
Please explain deep I can't understand.
Munna said:
1 decade ago
How we get 5/7 and 1-5/7=2/7 how it is possible tell me friend?
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)
Deepa said:
1 decade ago
Why we have calculated only for 5 days it may be 6 days too. ?
Singh said:
2 decades ago
Ankush you are genious yaar. You are 100% correct.
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