The hardness of a ground water sample was found to be $420 \mathrm{mg} / \mathrm{L}$ as $\mathrm{CaCO}_{3}$. A softener containing ion exchange resins was installed to reduce the total hardness to $75 \mathrm{mg} / \mathrm{L}$ as $\mathrm{CaCO}_{3}$ before supplying to 4 households. Each household gets treated water at a rate of $540 \mathrm{~L} /$ day. If the efficiency of the softener is $100 \%,$ the bypass flow rate (expressed in $\mathrm{L} /$ day $)$ is
The hardness of a ground water sample was found to be $420 \mathrm{mg} / \mathrm{L}$ as $\mathrm{CaCO}_{3}$. A softener containing ion exchange resins was installed to reduce the total hardness to $75 \mathrm{mg} / \mathrm{L}$ as $\mathrm{CaCO}_{3}$ before supplying to 4 households. Each household gets treated water at a rate of $540 \mathrm{~L} /$ day. If the efficiency of the softener is $100 \%,$ the bypass flow rate (expressed in $\mathrm{L} /$ day $)$ is