An experiment was conducted at a small supermarket for a period of 88 days on the sales of a single brand of dog food, involving three levels of shelf height: knee level, waist level, and eye level. during each day, the shelf height of the dog food was randomly changed on three different occasions. sales, in hundreds of dollars, of the dog food per day for the three shelf heights are given below. based on the data, is there a significant difference in the average daily sales of this dog food based on shelf height? use a 0.050.05 level of significance.