So, the fraction of races that he won was:

: you need ti divide the number of occurrences by the number of possibilities.
We can simplify this:

.
When we write it in decimals until the closest place, it's:
0.167 or 16.667%
Are you given an equation?
Answer:

Step-by-step explanation:
The half life is the amount of time it takes a substance to decay to half of its original amount.
Since the radioactive substance has a half life of 1000 years, there will be half of it left after 1000 years.
So, the fraction that will be left after 1000 years is 
I and -2 is the solve for the equation