"Two things are infinite: the universe and human stupidity; and I'm not sure about the universe."
- Albert Einstein
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?
2/15 is work is done by X and Y in 1 day.
And 4/5 is Remaining work
suppose X and Y together take A days to complete the remaining wotk then
A*2/15 = 4/5
now A = 4/5 * 15/2
so A = 6 days
i think you understood the logic behind that
Nikhil said:
(Fri, Aug 20, 2010 05:37:40 AM)
2/15 work done by x and y in one day.
Then how you are taking reciprocal 15/2*4/5.
Nagaraising said:
(Sun, Aug 29, 2010 12:33:06 PM)
Please explain about remaining work?.
Neeru said:
(Fri, Sep 3, 2010 06:17:40 AM)
Always total work will be considered as 1, in dat 1/5 th work is already done and the remaining work is 1-1/5 =4/5 dats it.
I hope you understand this.
Ramchandra said:
(Mon, Sep 20, 2010 04:52:47 AM)
Hai frnds this is very long process....
I can find one short cut ..i.e
Suppose x & Y do the work = k days (assume)
y do work = k-1 days
we now that
(x/20)+((x-4)/12))=1 ( By solving )
x=10 days...
Vikas said:
(Fri, Sep 24, 2010 08:32:28 AM)
Ramchandra please explain it clearly. It is not understandable.
Harsha said:
(Wed, Oct 13, 2010 08:48:44 AM)
In 1 day 1/20 th work.
Let us assume a takes x days to complte it
As B joins 4 days later he has only x-4 days remaining.
They both work respectively with their capacities and finish the one complete work
Hence
(1/20th work) * x days + (1/12th work) * (x-4) days = 1 full work
=> x/20 + (x-4)/12 = 1
=> x = 10days
Jjjjjjjjjj said:
(Thu, Oct 28, 2010 02:15:21 PM)
Please explain clealrly.
Mitra said:
(Sun, Oct 31, 2010 11:48:44 PM)
(x+4)/20 + x/12 = 1
solving x = 6 days
total days 4+6=10days
Lydia said:
(Tue, Nov 2, 2010 05:25:27 PM)
Please explain the remaining work.
Srikanth Chowdary said:
(Sat, Dec 25, 2010 01:36:25 AM)
Mitra please explain clearly.
Zeeshan said:
(Sun, Dec 26, 2010 10:11:52 AM)
Well done harsha.
Anwesh said:
(Mon, Dec 27, 2010 09:06:52 AM)
Harsha realy well done.
Sahib said:
(Mon, Jan 31, 2011 07:34:21 AM)
Take it this way
1/5 work x does in 4 days
Remaining 4/5 is to be found
X+y does 1/20+1/12 in 1 day
Therefore x+y=2/15 w/d
Therefore 4/5 w = 2/15(w/d)/4/5(w)
We get 1/6(1/d)
Therefore 6 days
Therefore total wrk in 10 days
Sree said:
(Wed, Mar 9, 2011 02:43:23 AM)
How 6+4?y should we add. Please help.
Santosh said:
(Wed, May 25, 2011 12:15:15 PM)
Well a simple logic
1day work x =1/20
y=1/12
x first start and works upto 4 days=4*1/20
then both x and y works upto some day to completework=a(1/20+1/12)
add (4*1/20)+a(1/20+1/12)=1
we will get the days where both x and y worked=a=6
So total days to complete work =4+6=10.
Swetha said:
(Tue, Aug 9, 2011 03:52:28 PM)
x can do a work in 20 days
y can do a work in 12 days
To find total work ,take LCM of 20 and 12 i.e 60
Therefore Total work =60
x's 1 day capacity =60/20 =3
Y's 1 day capacity =60/12 =5
Since x alone did work for 4 days,
4*3=12 ,
12 work done in 4 days
there fore remaining work = 60-12 =48
Remaining work was completed by both
remaining work / (x's per day capacity +y's per day capacity)=48/6= 6
therefore remaining work was completed in 6 days
Total work was completed in 4 + 6 = 10 days.
