A typical galaxy occupies a volume of about 1.00 × 1061 m3 and contains 1.00 × 1011 stars, each with an effective radius of 1.00 × 109 m. Determine
a. The collision probability of two stars within the galaxy.
b. The number of stars that will have experienced a collision by the time they have traveled a distance of 0.0100 mean free paths.