[Vroomfondel]

186,000 mps +- 4,321 mps (19 times out of 20), more or less.

I'm sorry, but these days the meter is defined in terms of the distance light travels in a second and the mile is defined in terms of meters, so there is no +/- on the speed of light in miles per second.

The metre is the length of the path travelled by light in vacuum during a time interval of 1/299 792 458 of a second.

In 1958 the United States and countries of the Commonwealth of Nations defined the length of the international yard to be exactly 0.9144 meters. Consequently, the international inch is defined to be exactly 25.4 millimeters.

[caveat emptor]