Question 10
To clean the city’s water, beavers built the filter network shown below. For correct treatment, water must pass through filters N, P and C in that order.
Valve 1 is open and the others are closed. How many of valves 2–6 could be opened while guaranteeing correctly treated water at the resulting outlet?
Valve 1 is open and the others are closed. How many of valves 2–6 could be opened while guaranteeing correctly treated water at the resulting outlet?