Answer
405.It's quite unlikely to find this many 2-year-old Corvettes in my region.
Work Step by Step
$\alpha=1-0.98=0.02.$ Using the table: $z_{\alpha/2}=z_{0.01}=2.33.$
Hence the sample size:$\left (\frac{z_{\alpha/2}\cdot \sigma}{E}\right)^2=\left (\frac{2.33\cdot 2157}{250}\right)^2\approx405$. It's quite unlikely to find this many 2-year-old Corvettes in my region.
