Answer:
d. 0.133
Step-by-step explanation:
-Standard error is calculated using the formula:
[tex]E=\frac{\sigma}{\sqrt{n}}\\\\\sigma-=standard \ deviation\\n=sample \ size[/tex]
#We substitute the given values in the formula to solve for E:
[tex]E=\frac{\sigma}{\sqrt{n}}\\\\=\frac{1.2}{\sqrt{81}}\\\\=0.133[/tex]
Hence, the standard error is 0.133 and the correct option is d