Answer: b. 0.85
Step-by-step explanation:
The formula to calculate the standard error is given by :-
[tex]S.E.=\dfrac{\sigma}{\sqrt{n}}[/tex]
We are given that the standard deviation of a population : [tex]\sigma = 7.8[/tex]
The sample size = 85
Therefore. the standard error of the mean is given by :-
[tex]S.E.=\dfrac{7.8}{\sqrt{85}}=0.846028785493\approx0.85[/tex]
Hence, the standard error of the mean = 0.85
