The wingspans of a common species of housefly are normally distributed with a mean of 15\,\text{mm}15mm15, start text, m, m, end text and a standard deviation of 0.5\,\text{mm}0.5mm0, point, 5, start text, m, m, end text. Suppose that a biologist regularly collects random samples of 202020 of these houseflies and calculates the sample mean wingspan from each sample.