To do this, you need to make sure that all speeds are the same unit. Since there are three 2 speeds already in km/hr, it would be best that you match the other 2 speeds into that unit as well.
Conversion of 15,000m/hr:
time is already in hours so you just need to make convert the meters to kilometers.
[tex]15,000\frac{m}{hr} * \frac{1km}{1,000m} = 15\frac{km}{hr} [/tex]
Conversion of 4.3m/s
[tex]4.3 \frac{m}{s} * \frac{3,600s}{1hr} * \frac{1km}{1000m} = 15.48 \frac{km}{hr} [/tex]
Now that they are all the same value, you can see that Fred at 4.3m/s was the fastest.
