The distance from the larger chromacity diagram's neutral point to the x-y coordinate was 4.5mm, and from the same neutral point, through the x-y coordinate to that diagram's curve was 41mm. Thus:

Excitation Purity = 4.5 / 41 X 100 = 11%
The Hexadecimal 24 bit value for the background color is "e0e0ff" or "e0" for Red, "e0" for Green, and "ff" for Blue. In Decimal this is 224 Red, 224 Green, and 256 Blue. If the Blue was also 224, then my background would be a light Grey. The extra 32 Blue makes this color light Blue instead. The Grey level for this color is 224, and since the White level of 256 is the maximum brightness, then the Luminous transmittance of this color is:  224 / 256 X 100 = 87.5%