cum....1.85 .2.85 ..3.79 ..4.65 .5.47 .6.29 ..7.12 ...7.96 ..8.82 .9.69
So I set up a quick-and-dirty equation:

4.65 over 132.2336 feet = X over 120 feet.

This gives a 40-yard dash time of 4.22 seconds.

So all those NFL Combine times of 4.1 seconds are now officially suspect.

K E N

Chris Johnson is listed with a 4.24 on this site:
http://www.nfl.com/combine/top-performers

He was timed at 10.38 seconds in the 100-meter sprint and ran the anchor leg on the fastest 4x100 relay team in the nation that won Golden South and Golden West national titles.
So I guess Bolt would run about 3.8 for 40 yards in the NFL, right?