Answer: 39
Step-by-step explanation:
Formula of sample size :
[tex]n=(\dfrac{z^c\times\sigma}{E})^2[/tex] , where [tex]z^c[/tex] = critical z-value for confidence level , [tex]\sigma[/tex] = population standard deviation , E = margin of error.
[tex]\Rightarrow\ n=(\dfrac{1.645\times7.5}{2})^2\\\\\Rightarrow\ n=(6.16875)^2=38.05347\approx39[/tex]
Hence, the minimum sample size that can be taken = 39
