Aptitude - Time and Work - Discussion
Discussion Forum : Time and Work - General Questions (Q.No. 28)
28.
X can do a piece of work in 40 days. He works at it for 8 days and then Y finished it in 16 days. How long will they together take to complete the work?
Answer: Option
Explanation:
| Work done by X in 8 days = |  |
1 | x 8 |  |
= | 1 | . |
| 40 | 5 |
| Remaining work = | |
1 - | 1 | |
= | 4 | . |
| 5 | 5 |
| Now, | 4 | work is done by Y in 16 days. |
| 5 |
| Whole work will be done by Y in | |
16 x | 5 | |
= 20 days. |
| 4 |
 X's 1 day's work = |
1 | , Y's 1 day's work = | 1 | . |
| 40 | 20 |
| (X + Y)'s 1 day's work = | |
1 | + | 1 | |
= | 3 | . |
| 40 | 20 | 40 |
| Hence, X and Y will together complete the work in | |
40 | |
= 13 | 1 | days. |
| 3 | 3 |
Discussion:
33 comments Page 4 of 4.
Anonymous said:
4 years ago
@All.
For those who are asking why 5/4 is multiplied,
Let's take an example, Suppose You complete work 1/2 of a work in 2 days. In how much time will you complete the entire work. 4 days right, how did you get it? you multiplied 2.
Eg:
1/2 : 2 is as 1: x, (I took 1 as it is the complete work).
Solving that, you still will get 4 as the answer. Same logic you can apply.
Thank you.
For those who are asking why 5/4 is multiplied,
Let's take an example, Suppose You complete work 1/2 of a work in 2 days. In how much time will you complete the entire work. 4 days right, how did you get it? you multiplied 2.
Eg:
1/2 : 2 is as 1: x, (I took 1 as it is the complete work).
Solving that, you still will get 4 as the answer. Same logic you can apply.
Thank you.
(4)
Shushma Gulla said:
1 year ago
@All.
X - 40
X finished it in 8 days then 40 ÷ 8 = 5.
The efficiency of X is 1/5.
Total efficiency is 1, then Y = 1 - 1/5 = 4/5.
Y finished work in 16 days;
Y days efficiency is 5/4 (reciprocal of Y work efficiency).
Then Y =5/4×16 = 20.
X = 40, Y = 20.
Lcm is 40 (total work)
X is 1 unit, Y is 2 units
Together completed work X, Y is 40/3 = 13(1/3).
X - 40
X finished it in 8 days then 40 ÷ 8 = 5.
The efficiency of X is 1/5.
Total efficiency is 1, then Y = 1 - 1/5 = 4/5.
Y finished work in 16 days;
Y days efficiency is 5/4 (reciprocal of Y work efficiency).
Then Y =5/4×16 = 20.
X = 40, Y = 20.
Lcm is 40 (total work)
X is 1 unit, Y is 2 units
Together completed work X, Y is 40/3 = 13(1/3).
Rajvardhan Patil said:
3 months ago
X -> 40 days He work for 8 days 40-8 = 32.
Y -> 16 Days: That 32 days work Y complete in 16 days means Y is double as efficient than X,
So, assume X = 100,
Y is double efficient so Y = 200.
Total Work = 100 * 20/100 + 200(if X & Y work together),
So, the Ans is A.
Y -> 16 Days: That 32 days work Y complete in 16 days means Y is double as efficient than X,
So, assume X = 100,
Y is double efficient so Y = 200.
Total Work = 100 * 20/100 + 200(if X & Y work together),
So, the Ans is A.
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