Suppose that Drake works for a research institute in Greenland and is given the job of treating wild polar bears there for hypothyroidism using medicated darts. The appropriate dosage depends on the bear's mass. Eager to head into the wilderness, he prints out the statistics he needs and sets off, planning to prepare the darts along the way.

Two days into his trek, however, Drake spills a cup of coffee on the printout. Unwilling to admit to his boss what happened, he decides to estimate the polar bear mass with the information he has remaining. He knows the population standard deviation to be σ=50 kg, and he has data from a simple random sample of n = 9 polar bears from Greenland. Their masses, in kg, are 390,340,325,410,280,350,390,375,290

The sample mean polar bear mass is x = .