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:
32 comments Page 4 of 4.
Bala said:
1 decade ago
Why you convert 4/5 into 5/4?
SHEIK said:
1 decade ago
x can do work=1/40--->1
Let 8x+16y=1---->2(which is x &y can do work)
sub x value in above equ. we get
8(1/40)+16y=1
y=1/20.
finally, x=y will together=(1/40)+(1/20)=3/40
Hence, ans is (40/3)=13 1/3 days...
Let 8x+16y=1---->2(which is x &y can do work)
sub x value in above equ. we get
8(1/40)+16y=1
y=1/20.
finally, x=y will together=(1/40)+(1/20)=3/40
Hence, ans is (40/3)=13 1/3 days...
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