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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.
A study found the mean concentration of sodium in softened water to be 278 mg/L. [23] In 2 liters of water—the amount of drinking water typically suggested for an average adult, this constitutes about 22% of the recommended sodium intake by the US CDC and may make a difference to those who need to significantly limit their sodium consumption.
Definitions. Volumetric water content, θ, is defined mathematically as: where is the volume of water and is equal to the total volume of the wet material, i.e. of the sum of the volume of solid host material (e.g., soil particles, vegetation tissue) , of water , and of air . Gravimetric water content[1] is expressed by mass (weight) as follows:
The study found that about 53% of total average household water use, or more than 192 US gallons (0.73 m 3) per household per day, was used for landscaping and other outdoor uses. Meanwhile, indoor use accounted for more than 170 US gallons (0.64 m 3) per household per day. The most in-home water consumption is toilet flushes, using 20% of the ...
Moisture meters are measuring instruments used to measure the percentage of water in a given substance. Direct gravimetric measurement of free moisture requires removing, drying, and weighing of a sample, so moisture sensors measure the volumetric water content indirectly by using some other property of the substrate, such as electrical resistance or dielectric constant.
Water metering is the practice of measuring water use. Water meters measure the volume of water used by residential and commercial building units that are supplied with water by a public water supply system. They are also used to determine flow through a particular portion of the system. In most of the world water meters are calibrated in cubic ...
At 20 °C (68 °F) one liter of water can dissolve about 357 grams of salt, a concentration of 26.3 percent by weight (% w/w). At 100 °C (212 °F) (the boiling temperature of pure water), the amount of salt that can be dissolved in one liter of water increases to about 391 grams, a concentration of 28.1% w/w.
A nautical mile is a unit of length used in air, marine, and space navigation, and for the definition of territorial waters. [2] [3] [4] Historically, it was defined as the meridian arc length corresponding to one minute ( 1 / 60 of a degree) of latitude at the equator, so that Earth's polar circumference is very near to 21,600 nautical miles (that is 60 minutes × 360 degrees).