Answer: 18
Step-by-step explanation:
The formula to find the minimum sample size is given by :_

, where
= population standard deviation.
z*= critical z-value.
E= Margin of error.
Given : 
E= ± 8
We know that critical value corresponding to 99% confidence level = z*=2.576 [Using z-table]
Then, the required sample size would be :


[Round to next integer.]
Hence, the required minimum sample size = 18
Answer:
2.5
Step-by-step explanation:
Answer:
Compass; straightedge.
Step-by-step explanation:
By using <span>De Moivre's theorem:
</span>
If we have the complex number ⇒ z = a ( cos θ + i sin θ)
∴
![\sqrt[n]{z} = \sqrt[n]{a} \ (cos \ \frac{\theta + 360K}{n} + i \ sin \ \frac{\theta +360k}{n} )](https://tex.z-dn.net/?f=%20%5Csqrt%5Bn%5D%7Bz%7D%20%3D%20%20%5Csqrt%5Bn%5D%7Ba%7D%20%5C%20%28cos%20%5C%20%20%5Cfrac%7B%5Ctheta%20%2B%20360K%7D%7Bn%7D%20%2B%20i%20%5C%20sin%20%5C%20%5Cfrac%7B%5Ctheta%20%2B360k%7D%7Bn%7D%20%29)
k= 0, 1 , 2, ..... , (n-1)
For The given complex number <span>⇒ z = 81(cos(3π/8) + i sin(3π/8))
</span>
Part (A) <span>
find the modulus for all of the fourth roots </span>
<span>∴ The modulus of the given complex number = l z l = 81
</span>
∴ The modulus of the fourth root =
Part (b) find the angle for each of the four roots
The angle of the given complex number =

There is four roots and the angle between each root =

The angle of the first root =

The angle of the second root =

The angle of the third root =

The angle of the fourth root =
Part (C): find all of the fourth roots of this
The first root =

The second root =

The third root =

The fourth root =
Answer:70 m
Step-by-step explanation: