**Answer:**

Infinity

**Step-by-step explanation:**

Since x,y,z are positive rel numbers, we have that

Hence,

Now let

if we take x=y=1, we have

and so f(1,1,z) tends to infinity as z goes to 0.

You will need:

(2240/625)*250=896 ml of treatment liquid.

If each bottle contains 250 ml you'll need 3.6 bottles (3 bottles and a bit more than half a bottle).

I do not think you need the conversion 1 cubic meter=1000 litres unless the volume of the tank is in cubic meters BUT 2240 cubic meters seems too large!

**Answer:**

800 ft

**Step-by-step explanation:**

2/3 minutes = 2/3 min * 60 sec/min = 40 sec = **t**

5 ft/sec = **r**

d= r * t = 5 ft/sec * 40 sec = 800 ft