Problem $2.$ Four million gallons per day $($MGD$)$ of wastewater, with a concentration of $12$ mgin of a conservative pollutant, is released into a stream having an upstream flow of $10$ MGD and a pollutant concentration of $2m\frac{g}{L}.$

$($a$)$ What is the concentration in $m\frac{g}{L}$ downstream of the wastewater discharge? $(12$ pts $)$

$($b$)$ How many pounds of substance per day pass a given spot downstream? $(6$ pts$)$

$($c$)$ If the pollutant limit is $4m\frac{g}{L}$ in drinking water, would this stream be a safe source of drinking water untreated with respect to this pollutant? Explain your reasoning. $(2$ pts $)$ Part B was wrong! $|$