The z scores corresponding to the mean weight of a rotten apple relative to the apples from either orchard are, respectively,
\(\dfrac{142-156}9\approx-1.56\)
\(\dfrac{165-156}{13}\approx0.69\)
The mean for the standard normal distribution is 0, which means that z scores closer to 0 represent data points that are more likely to occur. Therefore it's reasonable to believe that rotten apples occur more often in shipments from Zippy's.
