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?

13 1 days
3

15 days
20 days
26 days
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

Therefore 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:
31 comments Page 4 of 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...


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