Researchers fed cockroaches a sugar solution. Ten hours later, they dissected the cockroaches and measured the amount of sugar in various tissues. Here are the amounts (in micrograms) of d-glucose in the hindguts of 5 cockroaches:
55.95 68.24 52.73 21.50 23.78
(The standard deviation of this sample is 20.74.)
From previous work, the researchers expected the population of responses to be Normal. The insects are a random sample from a cockroach population grown in the laboratory. A 90% confidence interval for the mean amount of d-glucose in cockroach hindguts under these conditions is__________