A large metropolitan water district that uses water diverted from the same river is also planning to measure the water temperature at 100 randomly selected locations along the river. Because of sampling variability, the sample collected by the water district is likely to yield a sample mean water temperature different from the sample mean water temperature collected by the sport-fishing group. Let the random variable D represent the mean water temperature, in degrees Celsius, of 100 locations along the river selected at random by the large metropolitan water district