Answer:
80%
Step-by-step explanation:
To find percentage increase, we use the following formula:
Percentage Increase = 
Here
New means the latest value (which is 18 dancers)
Old means the previous value (which is 10 dancers)
The Multiplication by 100 is to convert the decimal answer to percentage.
So, we have:
New = 18
Old = 10
Now we substitute and find:

So, there was an increase of 80%
Your answers:
10) (m+7)(m+8) 11) (b-10)(b+2)
12) (k-4)(k+10) 13) (n-9)(n-8)
14) (7r+3)(r-2) 15) (5a+6)(a+2)
Hope it helps
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; 
Idk! Is there a picture to show us?
I think this is the correct answer: * Zc x (sigma/sqrt of n)
c= .95 (Zc of 1.96)
0.711*