How fast is 100 meters in 9.58 seconds?

The easiest way to figure out this or just about any other unit conversion problem is to convert the units you are changing first. In this case, 1 yard is only 0.9144 meters and therefore 100 yards is only 91.44 meters.

The unit you are NOT changing is the second so now you can set up a ratio:

9.52 seconds / 100 meters x 0.9144 meters / 1 yard = (9.52 * 0.9144) seconds / yard

which is 8.76 seconds when rounded to the same number of significant digits.

NOTE: What you asked for is merely a conversion and as such it is imperfect. Had the race actually been only 100 yards (which is 8.56 meters or just over 28 feet shorter), the runners could have decided to use different strategies and their speeds would then be very different.