To completely fill a half filled tank tap x is opened and the tank is fully filled in 20 hours

28hrs.....

tank fills half of the tank in 20 hrs i.e., it will take 40 hrs to fill the empty tank
in one hour tap fills 1/40 part of the tank
initially half of tank is filled i.e., 1/2
after 4 hrs power is gone. in 4 hrs tap fills (1/40)*4th part of tank= 1/10 part
now amount of water in tank is (1/2)+(1/10)=6/10
half of it is used.. hence now water in tank= 3/10
amount of water to be filled in tank is 1-(3/10)=7/10
time taken to fill 7/10 part of tank is (7/10)*40=28
10 years agoHelpfull: Yes(112) No(15)

tap fill the tank in 1 hour= 1/20
so tap fill the tank in 4 hr=1/5
now tank filled already 1/2 and after 4 hour tank filled by 1/2+1/5=7/10
during the cut off 7/20 water was used so now tank is empty by 13/20
tap fill tank in 1 hr=1/20
then tap fill 13/20 tank in hr=(13/20)*20=13hr
10 years agoHelpfull: Yes(20) No(22)
Let tank is of 100 liter so A/Q half is already filled ie 50 liter.
Now 20 Hours required to full the tank means 20 hours is reuired to fill 50 liter but after 4 hour power goes off it means only 10 liter water will come.
Now total water= 50+10= 60 liter
half is used means 30 liter
remaining empty= 70 liter
now, 10 liter = 4 hour
1 liter = 4/10 hour
70 liter = 4/10 * 70 = 28 hours
10 years agoHelpfull: Yes(18) No(0)
Imran is correct the corect answer is 28
10 years agoHelpfull: Yes(11) No(3)
13 ltr

Assume...
tank has volume of 20 liter.
20 hour to fill compleatly (i.e.the tank is fully filled in 20 hours. )
so every hour 1 ltr..

half filled tank==10 liter
4 hours filling==14 ltr
half water used==14/2 =7 ltr
remaining==20-7= 13 ltr

to fill 13 ltr-------13 hours required
10 years agoHelpfull: Yes(10) No(16)
In 1 hr it does 1/20*100= 5% work
so in 4 hr = 20% work
but tank is already full filled i.e. 50% work is already completed
after 4 hr 70% work is completed
when power goes off, half of water is used means 35% of water is used
i.e. when power backed then (100-35)%= 65% work is yet remaining
65% work is done in 13 hr.
answer: 13 hr
10 years agoHelpfull: Yes(9) No(2)
Ans: 13hrs.

In 20hrs full tank is filled.
In 1hr 1/20 part of the tank is filled.
In 4hrs 1/5 part of the tank is filled.
Already the tank was half filled,
thus now (1/5+1/2)=7/10 part of the tank is filled.
Now, given that half of the water has been used,
hence, 7/20 part of the water has been used.
Again, (7/10 - 7/20)=7/20 part of water is left in the tank.
Thus (1-7/20) = 13/20 remaining part of the tank is to be filled.

Now,
1/5 parts is filled in 4hrs.
1 parts will be filled in 4*5 = 20hrs.
13/20 parts will be filled in 20*13/20= 13hrs.
10 years agoHelpfull: Yes(6) No(4)
let be tank is of 20 litres
so half filled means it is 10 litre filled
after tap has been opened for 4 hours then its capacity becomes
10+4=14 litres
now after half hour half tank has been has been opened so
7 litres is remaining in tank
so tank is 13 litres empty and so needed 13 hours
so ans is 13 hours.
10 years agoHelpfull: Yes(5) No(1)
In 1 hr it does 1/20*100=5% work
So in 4 hr= 20%work
When light backed that time 1/2 of that is used so now it only 10% filled
Now we have to filled 90%
Since in 1hr it fill 5%
So 90% fill in 18 hr
And should be 18 hr
10 years agoHelpfull: Yes(4) No(11)
13 hours

1-let the work of tank filling be 1.
2-tank is 1/2 filled , only 1/2 is left.
3-it takes 20 hrs to fill the tank completely, thfr: 1 hr work is 1/20 of filled tank
4-in 4 hrs tank filled=4*1/20=1/5
5-now water in tank is 1/5+1/2=7/10
6-water used is 1/2of7/10=7/20
7-empty tank=1-7/20=13/20
8-timw to fill 13/20 of tank=20*13/20=13hrs
10 years agoHelpfull: Yes(3) No(0)
ans 16hr
as tank half already filled
and pipe x take time 20hr to filled fully
so for 4hr the tank filled are 12+(42*20)=610
exactly half of water is empty so remaining water is 35
so we have to filled 1-310=25 part of tank
25=110+110+110+110=4hr+4hr+4hr+4hr=16hr
10 years agoHelpfull: Yes(2) No(4)
suppose capacity x liter
now in 1 hr x/20 liter full
so in 4 hr =4*x/20=x/5
then 1/2 of filled used ,remaining= x/5-1/2(x/5)=x/10 liter
to fill completely amount required= x-x/10=9x/10
so to fill x liter require 20 hrs
so to fill 9x/10 require=18 hrs
10 years agoHelpfull: Yes(2) No(3)
its 13 hrs.
bcoz when light comes tank is 35% filled ,to fill it completely it takes 13 hrs.
10 years agoHelpfull: Yes(2) No(3)
half tank filled in=20hrs
to fill the full tank it will require=40hrs
let the full tank can hold=a lt of water

in 40 hrs tank filled=a litre
in 4 hrs tank filled=(a/40)*4=a/10
so after 4 hrs water left=(a/2+a/10)=12a/20
As it is saaid that half of the water is used..
now reamaining=(12a/20)/2 [dividing by 2]
=11a/40
so the water to be filled=a-(11a/40)
=28a/40
a liter filled=40 hhrs
1 liter filled=40/a
28a/40 liter filled=(40/a)*(28a/40)
28 hours.
10 years agoHelpfull: Yes(2) No(1)
half part already filled means i.e 1/2,
in 4 hours 1/5 part of 1/2 is also filled means =1/2*1/5=1/10
now amount of water in tank is=1/10+1/2=6/10=3/5
now half part of water had been used ...now water in tank =3/10
now amount of water to be filled in tank is 1-(3/10)=7/10,
so if 1/10 part can filled in 4 hours so 7/10 part can be filled in 7*4=28 hours
10 years agoHelpfull: Yes(2) No(0)
13 hrs

.
10 years agoHelpfull: Yes(1) No(3)
corect answer is 28hrs
10 years agoHelpfull: Yes(1) No(0)
According to me 28 hr is correct.
10 years agoHelpfull: Yes(1) No(0)
confusion is in understanding the question,ans is 13 only,if it was provided 28 in option i would have also ticked 28 as right,their concept is totally clear who have given answer as 28,question is such that its making us to think that the tank gets half filled in 20 hours,but " To completely fill a half filled tank tap x is opened "this statement is different which will be used in the question afterwards and, " the tank is fully filled in 20 hours" this statement is different.two different statements they are.SO IN QUESTION IT IS GIVEN THAT TANK GETS FILLED IN 20HRS ,NOT HALF FILLED
8 years agoHelpfull: Yes(1) No(0)
ANS. IS 13 HR
10 years agoHelpfull: Yes(0) No(0)
half of the tank is already full...now tap x fill 1/20 in 1 hour...it is open for 4 hours so ...net water content in tank will become 7/10....and now half of the water is used that means 7/20 is used ...we are left with 7/20..of water....and the portion of the tank which is empty is 13/20....so the time taken by the tap x to fill 13/20 of tank is 13 hours..is the answer
10 years agoHelpfull: Yes(0) No(0)
in 20 hours it is half filled, so for full tank it will take 40 hours.
in 4 hours the tank will be 4*(1/40)= 1/10.so total 1/2 + 1/10 = 3/5, after 4 hours power gone, then half used means, 3/5 - 1/2 = 1/10, remaining in tank, so 1-1/10 =9/10, so time will be 9/10 *40= 36 hours, so 16 hours.
10 years agoHelpfull: Yes(0) No(0)
12 hrs.........as half of the remaining water is used b efore the light came.
10 years agoHelpfull: Yes(0) No(1)
tap x takes 20 hours to fill half tank and to fill full tank it takes 40 hours.
when light goes off half tank water had been used. therefore tank has water which was filled by yap in 4 hours.
to fill tank completely tap takes= 16(as 4 hours water is already in tank)+20=36 hours
10 years agoHelpfull: Yes(0) No(0)
18 hrs is the correct ans.
9 years agoHelpfull: Yes(0) No(1)
Here total time is asked or how much time will be taken after 2 women leave is asked?
In 1st case answer is 70/3 and in 2nd case answer is 118/3.
9 years agoHelpfull: Yes(0) No(1)
13 hours
half already fill 1/2
in 4 hours fill 1/5
so total fill 1/2+1/5=7/10
then half has been used=7/20
remaining part=1/7/20=13/20
now required time=13*20/20=13
9 years agoHelpfull: Yes(0) No(1)
ITS FILLED UP IN 13 Hours
9 years agoHelpfull: Yes(0) No(1)
correct answer is 28, those who have not got 28 becoz they are not cosidering (1/2). in the question it is clearly written half filled tank means tank is already half filled.
9 years agoHelpfull: Yes(0) No(0)
before,
tank filled was 1/2 .
tank need to fill 1/2 need more 20 hr
therefore to fill complete empty tank =2* 20=40 hr
ATQ,
tank fill 1/2 before power cut,
in 4hr water fill will be 4/20=1/5
and we have tank fill total after power cut=1/5+1/2=7/10
in that 1/2 of water use therefore=7/10-1/2=2/10=1/5 water left in tank
to fill empty tank we need 40 hr,therefore we need 1/5*40=8hr+20hr (for half fill one)
ans will be 28hrs
9 years agoHelpfull: Yes(0) No(0)
Total time req. to fll the tank = 20Hr.
Work done in 1 Hr. = 1/20
Work Done in 4 Hr = (1/20) * 4 = 1/5

Now tank is 1/5th filled.
Water used = 1/2(1/5) = 1/10
Water left in tank = 1/10

Remaining part to be filled = (1-1/10) = 9/10

since 1/20 tank is filled in 1 hr, 9/10 tank would be filled in (9/10 * 20) hrs. i.e 18 hrs. [Unitay method]

So ans is 18 hrs.
9 years agoHelpfull: Yes(0) No(0)
either provide the question properly or kindly dont post... question with wrong options misguiding... Imran is right according to the question...
9 years agoHelpfull: Yes(0) No(0)
when half of the tank to be filled needs 20hr then obviously it will need more than 20hr.
After filling 4hr, water level now 60%,and after used it left with 30%,n now have to fill 70%.
But to fill 50%,it need 20hr.
so to fill 70% - 28hr needed.
Ans is 28hr.
9 years agoHelpfull: Yes(0) No(0)
13 hours is right ans.those people writing ans 28 ,18 and any other except 8,10,13,16,15,they are totally mad #LOL
8 years agoHelpfull: Yes(0) No(0)
50 % work --- 20 hrs
100% work --- 40 hrs
divide upper equation by 10
10% work ----4 hrs
50% is already filled and in 4 hrs 10% work will be done.So total 60%.
half of water is used so 30% tank is full. Remaining 70% will be filled in
100% ----40 hrs....So 1% ---- 40/100 and 70% --- (70*40)/100
Ans : 28 hrs
8 years agoHelpfull: Yes(0) No(0)

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