Question

How do I solve for n?

\[\dfrac{2}{9}(n^2-n)\times0.6^n=0.121\]

Answer 1

This is what I did so far \[(n^2-n)0.6^n=0.5445\]

Answer 2

it doesn't look like there is a nice algebra way to do this
http://www.wolframalpha.com/input/?i=%5Cdfrac%7B2%7D%7B9%7D%28n%5E2-n%29%5Ctimes0.6%5En%3D0.121

Answer 3

Well it should be possible as it is in a binomial distribution question

Answer 4

Do you know a non-nice way to do this?

Answer 5

you could plot it. type
plot (x^2 - x)*0.6^x
in the google search window. That will give you a rough idea of the solution.

and of course wolfram can solve it.
or use numerical root finding algorithm e.g. Newton-Raphson