A liter of water weighs a kilogram so 15 mg/kg = 15 ppm on a mass over mass basis. If that is the flavor of ppm you want, done. But ppm can also be computed on a volume basis, molar ratio, etc. It is better tio use a clear form with units that identifies the basis such as mg/kg.
Serena Williams knocked off Lucie Safarova in the final of the women's draw at the French Open, and Bovada has her listed as the clear favorite on the odds to win Wimbledon this year; Williams sits as the 7/4 chalk on those betting lines.
With the exception of Roger Federer, there is no greater Wimbledon champion in either field than Venus Williams. Along with her sister, Serena, the Williams sisters have won five Wimbledons a piece, which would ordinarily guarantee some special privileges and perks, even if Venusâs last title was seven years ago. But Wimbledon has been doing Miss Vee dirty on the first week of the fortnight.