What is the probability that a random mutation

Assume the following:

• There are approximately 3,000,000,000 base pairs in the mammalian genome (genes constitute only a small portion of this total).
• There are approximately 10,000 genes in the mammalian genome.
• A single gene averages 10,000 base pairs in size.

In the mammalian genome:
1. How many total base pairs are in all the mammalian genes?

2. What proportion (%) of the total genome does this represent?

3. What is the probability that a random mutation will occur in any given gene?

4. Only 1 out of 3 mutations that occur in a gene result in a change to the protein structure. What is the probability that a random mutation will change the structure of a protein?