Answer:
And rounded up we have that n=421
Step-by-step explanation:
We know that the sample proportion have the following distribution:
In order to find the critical value we need to take in count that we are finding the interval for a proportion, so on this case we need to use the z distribution. Since our interval is at 90% of confidence, our significance level would be given by 
and 
. And the critical value would be given by:
The margin of error for the proportion interval is given by this formula:
(a)
And on this case we have that 
and we are interested in order to find the value of n, if we solve n from equation (a) we got:
(b)
We assume that a prior estimation for p would be 
since we don't have any other info provided. And replacing into equation (b) the values from part a we got:
And rounded up we have that n=421
The extraneous root is
x = 2
Answer:
The side length is 9m
Step-by-step explanation:
A = 81 m^2
Since the figure is a square, we know the area of a square is A = s^2 where s is the side length
81 m^2 = s^2
Take the square root of each side
sqrt(81 m^2 ) = sqrt( s^2)
9 m = s
The side length is 9m
We know:
and
These expressions have an 
term in common. We can combine them if we can find forms of the expressions in terms of :
Now, because 
(by the reflexive property), we can write:
This is our answer, A.
