If we imagine that 1 in 10 million stars would eventually give ...

[rosent76]

If we imagine that 1 in 10 million stars would eventually give rise to a civilization on an orbiting planet and assuming that there are 100 billion stars in our Milky Way galaxy, how often should a civilization randomly appear over a 5 billion year
 
  period? A) once every 50 million years
  B) once every 50,000 years
  C) once every 500,000 years
  D) once every 5 million years

Question 2

Rayleigh scattering would have 400. nm light be scattered how many times as much as 800. nm light?
 
  A) 32
  B) 4
  C) 8
  D) 2
  E) 16

[Jadwiga9]

Answer to Question 1

C

Answer to Question 2

E