Answer: A. 1.2
Step-by-step explanation:
Given : Sample size : n= 64
Standard deviation: [tex]\sigma=9.6[/tex]
The formula to find the standard error of mean is given by :-
[tex]S.E.=\dfrac{\sigma}{\sqrt{n}}\\\\\Rightarrow\ S.E.=\dfrac{9.6}{\sqrt{64}}\\\\\Rightarrow\ S.E.=\dfrac{9.6}{8}=1.2[/tex]
Therefore, the standard error of the mean= 1.2
Hence, A is the right option.