Answer:
B. z = 2.14; s = 4; n = 81
Step-by-step explanation:
We know that,
[tex]\text{Margin of error}=z\cdot \dfrac{\sigma}{\sqrt n}[/tex]
Putting the values,
z = 2.14; s = 4; n = 9
[tex]\text{Margin of error}=2.14\cdot \dfrac{4}{\sqrt 9}=2.85[/tex]
z = 2.14; s = 4; n = 81
[tex]\text{Margin of error}=2.14\cdot \dfrac{4}{\sqrt{81}}=0.95[/tex]
z = 2.14; s = 16; n = 9
[tex]\text{Margin of error}=2.14\cdot \dfrac{16}{\sqrt 9}=11.41[/tex]
z = 2.14; s = 16; n = 81
[tex]\text{Margin of error}=2.14\cdot \dfrac{16}{\sqrt{81}}=3.80[/tex]
