Answer:
0.25 feet per minute
Step-by-step explanation:
Gravel is being dumped from a conveyor belt at a rate of 20 ft3/min. Since we are told that the shape formed is a cone, the rate of change of the volume of the cone.


Since base diameter = Height of the Cone
Radius of the Cone = h/2
Therefore,


Therefore: 
We want to determine how fast is the height of the pile is increasing when the pile is 10 feet high.

When the pile is 10 feet high, the height of the pile is increasing at a rate of 0.25 feet per minute
Answer:
depends on how many miles you can go on 1 mile.
The sample size should be 250.
Our margin of error is 4%, or 0.04. We use the formula

To find the z-score:
Convert 98% to a decimal: 0.98
Subtract from 1: 1-0.98 = 0.02
Divide both sides by 2: 0.02/2 = 0.01
Subtract from 1: 1-0.01 = 0.99
Using a z-table (http://www.z-table.com) we see that this value has a z-score of approximately 2.33. Using this, our margin of error and our proportion, we have:

Divide both sides by 2.33:

Square both sides:

Multiply both sides by n:

Divide both sides to isolate n: