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For an approximately normal data set, the values within one standard deviation of the mean account for about 68% of the set; while within two standard deviations account for about 95%; and within three standard deviations account for about 99.7%. Shown percentages are rounded theoretical probabilities intended only to approximate the empirical ...
In toxicology, the median lethal dose, LD 50 (abbreviation for "lethal dose, 50%"), LC 50 (lethal concentration, 50%) or LCt 50 is a toxic unit that measures the lethal dose of a given substance. [1] The value of LD 50 for a substance is the dose required to kill half the members of a tested population after a specified test duration.
In granulometry, the particle-size distribution (PSD) of a powder, or granular material, or particles dispersed in fluid, is a list of values or a mathematical function that defines the relative amount, typically by mass, of particles present according to size. [1]
If a data distribution is approximately normal then about 68 percent of the data values are within one standard deviation of the mean (mathematically, μ ± σ, where μ is the arithmetic mean), about 95 percent are within two standard deviations (μ ± 2σ), and about 99.7 percent lie within three standard deviations (μ ± 3σ).
Absolute humidity is the total mass of water vapor present in a given volume or mass of air. It does not take temperature into consideration. Absolute humidity in the atmosphere ranges from near zero to roughly 30 g (1.1 oz) per cubic metre when the air is saturated at 30 °C (86 °F).
Each row of points is a sample from the same normal distribution. The colored lines are 50% confidence intervals for the mean, μ. At the center of each interval is the sample mean, marked with a diamond. The blue intervals contain the population mean, and the red ones do not.
The crude death rate is defined as "the mortality rate from all causes of death for a population," calculated as the "total number of deaths during a given time interval" divided by the "mid-interval population", per 1,000 or 100,000; for instance, the population of the U.S. was around 290,810,000 in 2003, and in that year, approximately 2,419,900 deaths occurred in total, giving a crude death ...
MyPlate is the latest nutrition guide from the USDA. The USDA's first dietary guidelines were published in 1894 by Wilbur Olin Atwater as a farmers' bulletin. [4] Since then, the USDA has provided a variety of nutrition guides for the public, including the Basic 7 (1943–1956), the Basic Four (1956–1992), the Food Guide Pyramid (1992–2005), and MyPyramid (2005–2013).