A ratio compares the frequency of one value for a variable with another value for the variable. The first value identified in a ratio must be to the left of the colon (:) and the second value must be to the right of the colon (1st value : 2nd value).
The Canadian two-dollar coin, commonly called the toonie, is the most valuable of the frequently used Canadian coins. It was introduced on February 19, 1996, by Public Works minister Diane Marleau.
The first use of adjusted fluoride in water for caries control began in 1945 and 1946 in the United States and Canada, when the fluoride concentration was adjusted in the drinking water supplying four communities (2--5).