Given these assumptions, we know the following. 1  The expected value of the difference between all possible sample means is equal to the difference between population means. 2  Thus, E(x 1 - x 2) = Î¼ d = Î¼ 1 - Î¼ 2. 3  The standard deviation of the difference between sample means (Ï d) is approximately equal to:
Guide to Joplin weather in December. The average maximum daytime temperature in Joplin in December is a cool 8Â°C (46Â°F). The average night-time temperature is usually a very cold -3Â°C (27Â°F). There are usually 5 hours of bright sunshine each day, which represents 51% of the 10 hours of daylight.
Missouri has a continental climate, but with considerable local and regional variation. The average annual temperature is 50Â°F (10Â°C) in the northwest, but about 60Â°F (16Â°C) in the southeast. Kansas City has a normal daily mean temperature of 54Â°F (12Â°C), ranging from 26Â°F (â3Â°C) in January to 79Â°F (26Â°C) in July; St. Louis has an annual mean of 56Â°F (13Â°C) with 29Â°F (â2Â°C) in January and 80Â°F (27Â°C) in July.