# Question

Refer to Problem 10.
In problem In the Southern Ocean food web, the krill species Euphausia superba is the most important prey species for many marine predators, from seabirds to the largest whales. Body lengths of the species are normally distributed with a mean of 40 mm and a standard deviation of 12 mm.
a. Determine the percentage of all samples of four krill that have mean lengths within 9 mm of the population mean length of 40 mm.
b. Obtain the probability that the mean length of four randomly selected krill will be within 9 mm of the population mean length of 40 mm.
c. Interpret the probability you obtained in part (b) in terms of sampling error.
d. Repeat parts (a)-(c) for samples of size 9.

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