- 37

- 0

**1. The problem statement, all variables and given/known data**

http://img16.imageshack.us/img16/2327/nummer1.jpg [Broken]

**2. Relevant equations**

S

_{n}=(u

_{1}(r

^{n}-1))/(r-1)

**3. The attempt at a solution**

I think i need to use the equation for geometric series(above). Or do i use the arithmetic furmula since ln(a/b)=ln(a)-ln(b). I think i am a bit confused...

Last edited by a moderator: