In the United States, a "quarter" is a common informal term used to refer to a quarter of various units of measurement, such as a quarter of a dollar, a quarter of a year, or a quarter of other divisible quantities. However, when used in the context of weight or mass, a "quarter" typically refers to a quarter of a hundredweight (cwt).
Since a hundredweight (cwt) in the United States is equal to 100 pounds (lbs), a quarter of a hundredweight is equal to:
1 quarter (US) = 25 pounds (lbs)
So, when you see "quarter" used in the context of weight or mass in the United States, it generally means 25 pounds. This term is often used informally, especially in agricultural or trade contexts, to refer to a convenient fraction of weight.
A nanogram (ng) is a metric unit of mass in the International System of Units (SI). It represents one billionth of a gram or 10^-9 grams. The metric system is a decimal-based system of measurement used worldwide, and it provides a convenient way to express very small quantities of mass.
To put the size of a nanogram into perspective:
Nanograms are commonly used in various scientific and analytical fields where precise measurements of tiny quantities of substances or particles are necessary. Some examples of their usage include: