Since we are not given any information about the proportion, we will assume the sample proportion to be 0.50
so,
p = 0.50
The Error is 10% percentage point. This means that on either side of the population proportion the error is 5% so E = 0.05
z = 1.645 (Z value for 90% confidence interval)
The margin of error for population proportion is calculated as:
This means 271 students should be included in the sample
For a hyperbola

where

the directrix is the line

and the focus is at (0, c).
Here, we have c = 5, a² = 9, so b² = 5² - 9 = 16.
a = √9 = 3
b = √16 = 4
Your hyperbola's constants are ...
a = 3
b = 4
______
Please note that the equation of a hyperbola has a negative sign for one of the terms. The equation given in your problem statement is that of an ellipse.
-3(y+2)^2-5+6y
-3(y^2+4y+4)-5+6y
-3y^2-12y-12-5+6y
-3y^2-6y-17
pi radians in a semicircle (half circle)
2pi radians in a full circle.
2pi = 2*3.14 = 6.28 approximately, so there are approximately 6.28 radians in a half circle.
2pi radians is equivalent to 360 degrees.