Answer: 95% confidence interval would be (81.95,84.45).
Step-by-step explanation:
Since we have given that
n = 100
mean = 83.2
Standard deviation = 6.4
So, At 95% confidence interval, z = 1.96
so, interval would be
[tex]\bar{x}\pm z\dfrac{\sigma}{\sqrt{n}}\\\\=83.2\pm 1.96\times \dfrac{6.4}{\sqrt{100}}\\\\=83.2\pm 1.2544\\\\=(83.2-1.2544,83.2+1.2544)\\\\=(81.95,84.45)[/tex]
Hence, 95% confidence interval would be (81.95,84.45).