The susceptibility of the root stocks of a variety of orange tree to a specific

larva is investigated by a group of researchers. Forty orange trees are exposed to

the larva and then examined by the researchers 6 months after exposure. The

number of larvae per gram is recorded on each root stock. The mean and

standard deviation of the logarithm of the counts are recorded to be 9.02 and

1.12, respectively.

a. Use the sample information to construct a 90% confidence interval on the

mean of the logarithm of the larvae counts.

b. Identify the population of which this confidence interval could be used to

assess the susceptibility of the orange trees to the larva.