Answer:
The correct option is A.
Step-by-step explanation:
Sample size(n)= 196
Sample mean = 12 ug/m³
Standard deviation (s)= 3.5 ug/m³
The formula for confidence interval is
[tex]C.I=\bar{x}\pm z^*\times \frac{s}{\sqrt{n}}[/tex]
Where, [tex]\bar{x}[/tex] is sample mean, s is sample standard deviation, n is sample size and z* is z-score at given confidence limit.
The value of z-score at 99.7% is 3.
[tex]C.I=12\pm 3\times \frac{3.5}{\sqrt{196}}[/tex]
[tex]C.I=12\pm 0.75[/tex]
[tex]C.I=[12-0.75,12+0.75][/tex]
[tex]C.I=[11.25,12.75][/tex]
The required solution is 11.25 ug/m³ - 12.75 ug/m³.
Therefore the correct option is A.
