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Percentage. In mathematics, a percentage (from Latin per centum 'by a hundred') is a number or ratio expressed as a fraction of 100. It is often denoted using the percent sign (%), [1] although the abbreviations pct., pct, and sometimes pc are also used. [2] A percentage is a dimensionless number (pure number), primarily used for expressing ...
In statistics, the 68–95–99.7 rule, also known as the empirical rule, and sometimes abbreviated 3sr, is a shorthand used to remember the percentage of values that lie within an interval estimate in a normal distribution: approximately 68%, 95%, and 99.7% of the values lie within one, two, and three standard deviations of the mean, respectively.
Each standard deviation represents a fixed percentile. Thus, rounding to two decimal places, −3σ is the 0.13th percentile, −2σ the 2.28th percentile, −1σ the 15.87th percentile, 0σ the 50th percentile (both the mean and median of the distribution), +1σ the 84.13th percentile, +2σ the 97.72nd percentile, and +3σ the 99
If there are 2 oranges and 3 apples, the ratio of oranges to apples is 2:3, and the ratio of oranges to the total number of pieces of fruit is 2:5. These ratios can also be expressed in fraction form: there are 2/3 as many oranges as apples, and 2/5 of the pieces of fruit are oranges.
Alcohol by volume (abbreviated as alc/vol or ABV) is a standard measure of the volume of alcohol contained in a given volume of an alcoholic beverage, expressed as a volume percent. [1][2][3] It is defined as the number of millilitres (mL) of pure ethanol present in 100 mL (3.5 imp fl oz; 3.4 US fl oz) of solution at 20 °C (68 °F).
The top grade, A, is given here for performance that exceeds the mean by more than 1.5 standard deviations, a B for performance between 0.5 and 1.5 standard deviations above the mean, and so on. [18] Regardless of the absolute performance of the students, the best score in the group receives a top grade and the worst score receives a failing grade.
Mass fraction (chemistry) In chemistry, the mass fraction of a substance within a mixture is the ratio (alternatively denoted ) of the mass of that substance to the total mass of the mixture. [1] Expressed as a formula, the mass fraction is: Because the individual masses of the ingredients of a mixture sum to , their mass fractions sum to unity:
English style guides prescribe writing the percent sign following the number without any space between (e.g. 50%). [sources 1] However, the International System of Units and ISO 31-0 standard prescribe a space between the number and percent sign, [8] [9] [10] in line with the general practice of using a non-breaking space between a numerical value and its corresponding unit of measurement.