To make $100$ L of solution, $1\mathrm{.}5$ kg salts is dissolved in water. Pure water is

pumped into a tank containing this solution at a rate of $5$ L$/$min$,$ salt solution

overflows at the same rate. The tank is well mixed. How much salt is in the tank at

the end of $15$ min? As the salt solution is dilute, assume that its density is

constant and equal to that of water.