The pesticide diazinon is commonly used to treat infestations of the German cockroach, Blattella germanica. A study investigated the persistence of this pesticide on various types of surfaces. Researchers applied a 0.5% emulsion of diazinon to glass and plasterboard. After 14 days, they randomly assigned 72 cockroaches to two groups of 36, placed one group on each surface, and recorded the number that died within 48 hours. On glass, 18 cockroaches died, while on plasterboard, 25 died. If p₁ and p₂ are the true proportions of cockroaches like these that would die within 48 hours on glass treated with diazinon and on plasterboard treated with diazinon, respectively, check if the conditions for calculating a confidence interval for p₁ − p₂ are met.