The eating habits of 12 bats were examined in the article "Foraging Behavior of the Indian False Vampire Bat" (Biotropica [1991]: 63-67). These bats consume insects and frogs. For these 12 bats, the mean time to consume a frog was x = 21.9 minutes. Suppose that the standard deviation was s = 7.7 minutes. Construct and interpret a 90% confidence interval for the mean suppertime of a vampire bat whose meal consists of a frog. What assumptions must be reasonable for the one-sample t interval to be appropriate?