Aptitude - Time and Work
Exercise : Time and Work - General Questions
- Time and Work - Formulas
- Time and Work - General Questions
- Time and Work - Data Sufficiency 1
- Time and Work - Data Sufficiency 2
- Time and Work - Data Sufficiency 3
16.
X and Y can do a piece of work in 20 days and 12 days respectively. X started the work alone and then after 4 days Y joined him till the completion of the work. How long did the work last?
Answer: Option
Explanation:
| Work done by X in 4 days = |  |
1 | x 4 |  |
= | 1 | . |
| 20 | 5 |
| Remaining work = | |
1 - | 1 | |
= | 4 | . |
| 5 | 5 |
| (X + Y)'s 1 day's work = | |
1 | + | 1 | |
= | 8 | = | 2 | . |
| 20 | 12 | 60 | 15 |
| Now, | 2 | work is done by X and Y in 1 day. |
| 15 |
| So, | 4 | work will be done by X and Y in | |
15 | x | 4 | |
= 6 days. |
| 5 | 2 | 5 |
Hence, total time taken = (6 + 4) days = 10 days.
17.
A is 30% more efficient than B. How much time will they, working together, take to complete a job which A alone could have done in 23 days?
Answer: Option
Explanation:
Ratio of times taken by A and B = 100 : 130 = 10 : 13.
Suppose B takes x days to do the work.
Then, 10 : 13 :: 23 : x  x = |
|
23 x 13 | |
x = |
299 | . |
| 10 | 10 |
| A's 1 day's work = | 1 | ; |
| 23 |
| B's 1 day's work = | 10 | . |
| 299 |
| (A + B)'s 1 day's work = | |
1 | + | 10 | |
= | 23 | = | 1 | . |
| 23 | 299 | 299 | 13 |
Therefore, A and B together can complete the work in 13 days.
18.
Ravi and Kumar are working on an assignment. Ravi takes 6 hours to type 32 pages on a computer, while Kumar takes 5 hours to type 40 pages. How much time will they take, working together on two different computers to type an assignment of 110 pages?
Answer: Option
Explanation:
| Number of pages typed by Ravi in 1 hour = | 32 | = | 16 | . |
| 6 | 3 |
| Number of pages typed by Kumar in 1 hour = | 40 | = 8. |
| 5 |
| Number of pages typed by both in 1 hour = | |
16 | + 8 | |
= | 40 | . |
| 3 | 3 |
 Time taken by both to type 110 pages = |
|
110 x | 3 | |
hours |
| 40 |
| = 8 | 1 | hours (or) 8 hours 15 minutes. |
| 4 |
19.
A, B and C can complete a piece of work in 24, 6 and 12 days respectively. Working together, they will complete the same work in:
Answer: Option
Explanation:
| Formula: If A can do a piece of work in n days, then A's 1 day's work = | 1 | . |
| n |
| (A + B + C)'s 1 day's work = | |
1 | + | 1 | + | 1 | |
= | 7 | . |
| 24 | 6 | 12 | 24 |
| Formula: If A's 1 day's work = | 1 | , | then A can finish the work in n days. |
| n |
| So, all the three together will complete the job in | |
24 | days |
= | 3 | 3 | days. | 7 | 7 |
20.
Sakshi can do a piece of work in 20 days. Tanya is 25% more efficient than Sakshi. The number of days taken by Tanya to do the same piece of work is:
Answer: Option
Explanation:
Ratio of times taken by Sakshi and Tanya = 125 : 100 = 5 : 4.
Suppose Tanya takes x days to do the work.
| 5 : 4 :: 20 : x x = |
|
4 x 20 | |
| 5 |
x = 16 days.
Hence, Tanya takes 16 days to complete the work.
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