Answer :
Answer: 12
Step-by-step explanation:
The formula to find the sample size is given by:-
[tex]n=(\dfrac{z_c\cdot \sigma}{E})^2[/tex] , where [tex]\sigma[/tex] is the population standard deviation, [tex]z_c[/tex] is the z-value for the [tex](1-\alpha)[/tex] confidence interval and E is the margin of error .
As per given , we have
Population standard deviation : [tex]\sigma=5.1[/tex]
z-value for 95% confidence interval : [tex]z_c=1.960[/tex]
Margin of error : E= 3
Then, the required minimum sample :-
[tex]n=(\dfrac{(1.96)\cdot (5.1)}{3})^2\\\\\Rightarrow\ n=(3.332)^2=11.102224\approx12[/tex]
Hence, the required minimum sample size = 12