On first day the tank had 8000 liters of water.
Half is removed so half of 8000 is 4000.
Subtracting 8000-4000 =4000
So at the end of first day 4000 liters of water is there.
Water in the tank at the end of second day:
Again half of 4000 is removed.
half of 4000 is 2000.
subtracting 4000-2000 =2000.
At the end of second day 2000 l of water is present in tank.
At the end of third day:
Again half of 2000 is removed.
half of 2000 is 1000.
subtracting 2000-1000 =1000.
At the end of third day 1000 l of water is present in tank.
At the end of fourth day:
Again half of 1000 is removed.
half of 1000 is 500.
subtracting 1000-500 =500.
At the end of fourth day 500 l of water is present in tank.
At the end of fifth day:
Again half of 500 is removed.
half of 500 is 250.
subtracting 500-250=250.
At the end of fifth day 250 l of water is present in tank.
At the end of sixth day:
Again half of 250 is removed.
half of 250 is 125.
subtracting 250 - 125 =125.
At the end of sixth day 125 l of water is present in tank.
At the end of seventh day:
Again half of 125 is removed.
half of 125 is 62.5.
subtracting 125-62.5 =62.5.
At the end of seventh day 62.5 l of water is present in tank.
At the end of eighth day:
Again half of 62.5 is removed.
half of 62.5 is 31.25
subtracting 62.5 - 31.25 =31.25.
At the end of eighth day 31.25 l of water is present in tank.