An agricultural researcher plants 25 plots with a new variety of yellow corn. Assume that the yield per acre for the new variety of yellow corn follows a Normal distribution with unknown mean $\mu$ and standard deviation $\sigma=10$ bushels per acre. 7. If the average yield for these 25 plots is $\bar{x}=150$ bushels per acre what is a $90 %$ confidence interval for $\mu$ ? A) $150 \pm 0.784$ B) $150 \pm 2.00$ C) $150 \pm 3.29$ D) $150 pm 3.92$ SP.AS. 1158