I do not know the last question but I know the first it is4 time I hope I am right
Answer:
the rate of change of the water depth when the water depth is 10 ft is; 
Step-by-step explanation:
Given that:
the inverted conical water tank with a height of 20 ft and a radius of 8 ft is drained through a hole in the vertex (bottom) at a rate of 4 ft^3/sec.
We are meant to find the rate of change of the water depth when the water depth is 10 ft.
The diagrammatic expression below clearly interprets the question.
From the image below, assuming h = the depth of the tank at a time t and r = radius of the cone shaped at a time t
Then the similar triangles ΔOCD and ΔOAB is as follows:
( similar triangle property)


h = 2.5r

The volume of the water in the tank is represented by the equation:



The rate of change of the water depth is :

Since the water is drained through a hole in the vertex (bottom) at a rate of 4 ft^3/sec
Then,

Therefore,

the rate of change of the water at depth h = 10 ft is:




Thus, the rate of change of the water depth when the water depth is 10 ft is; 
For this case we have the following number:
600,000
We can rewrite this number as the product of two numbers.
We have then, mathematically:
600,000 = 60 * 10,000
Then, rewriting in words we have:
600,000 = sixty - ten thousand
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Answer:
Rewriting 600,000 we have:
600,000 = sixty - ten thousands
1. $.0999 = $.1
2. $2.0192 = $2.02
3. $21.5953 = $21.60
4. $35.6667 = $35.67
5. $1.3999 = $1.40
6. $25.3333 = $25.33