The equation for speed is:
[tex] S =\frac{d}{t} [/tex]
The student ran 100 meters in 11 seconds. Our distance is 100 meters and our time is 11 seconds.
[tex] S =\frac{100m}{11s} [/tex]
When we solve we get the following:
[tex] S = 9.09m/s [/tex]
I am guessing since you were given the unit conversion of 1 mile = 1609 meters, you need to answer in miles per hour. If you do, you will need to use dimensional analysis:
[tex] \frac{9.09m/s}{1} *\frac{1mi}{1609m} *\frac{3600s}{1hr} =\frac{32724mi}{1609hr} = 20.34mi/hr [/tex]
All of the units except miles and hour cancel out, which makes this problem valid. Your answer in mph (mi/hr) would be:
20.34 miles per hour