Arsenic-based additives in chicken feed have been banned by the European Union but are mixed in the diet of about of the billion broiler chickens produced annually in the US.1 Many restaurant and supermarket chains are working to reduce the amount of arsenic in the chicken they sell. To accomplish this, one chain plans to measure, for each supplier, the amount of arsenic in a random sample of chickens. The chain will cancel its relationship with a supplier if the sample provides sufficient evidence that the average amount of arsenic in chicken provided by that supplier is greater than ppb (parts per billion). If a restaurant chain finds significant evidence that the mean arsenic level is above , the chain will stop using that supplier of chicken meat. The hypotheses are: ,