10.15 Eighteen fish of a comparable size in a particular variety are divided randomly into three groups and each group is prepared by a different chef using the same recipe. Each prepared fish is then rated on each of the criteria of aroma, flavor, texture, and moisture by professional tasters. Use the composite scores below to test the null hypothesis that median scores for all three chefs are the same.

Chef A Chef B Chef C 4.05 4.35 2.24 5.04 3.88 3.93 3.45 3.02 3.37 3.57 4.56 3.21 4.23 4.37 2.35 4.18 3.31 2.59