Manufacturing and Product Development During Summer 2013, Procter and Gamble (P&G) recalled 30 different types of cat and dog food because they may have been contaminated with Salmonella. While pets can become ill from eating contaminated foods, the Centers for Disease Control and Prevention also reminded people to wash their hands thoroughly after handling pet food. Independent random samples of P&G cat foods and dog foods were obtained, and each was tested for Salmonella.
For cat food, n1 = 1250 and 50 were contaminated, and for dog food, n2 = 1448 and 87 were contaminated. Is there any evidence to suggest that the true proportion of contaminated cat food is different from the true proportion of contaminated dog food? Use a = 0.05.