Agents of the Drug Enforcement Administration seize 5000 1-kg "bricks" containing a light tan powder that is suspected to contain heroin. Historically, such seizures are all pure heroin. Outwardly, all the packages appear similar. Use the ENFSI spreadsheet to select the number of samples that need to be collected and tested for the DEA to be 90% confident that at least 90% of the packages contain heroin.