I actually did exactly that just before you posted and 5/8 isn't the answer either. I tried .625 too and it's not taking it. I can't figure out what is wrong.
I actually did exactly that just before you posted and 5/8 isn't the answer either. I tried .625 too and it's not taking it. I can't figure out what is wrong.
The result of ratio test you got tells you its convergent. It doesn't tell you what the value of the sum is.
Do what o_O suggested and break it up into two geometric series.