The "exact 50%", or the boundary between green and blue, is nominally hue 180, which is cyan. A search for the RGB, CMYK and HSL for turquoise yielded a few hue values from 171 to 174 (depending who you trust, and allowing for a bit of drift due to colorspace conversions). In any case, 171, 172, 173, and 174 are all on the green side of cyan.