Geometric Progressions

This is a dumb question, but idc.

In geometric investment type problems, what is the meaning of interest? also how do you calculate common ratio will be when given an interest percentage.

This question:
https://gyazo.com/ce01cfbe03619d817460aa4d760a63fd

Interest of 4%, for instance, means that after a year, in this case, could be different unit of time, that his cash increases by 4%, or if you prefer by a factor of 1.04 (what he already has is 100% then you add 4% which is 4/100 or 0.04)

Hi, again! Could you tell me where I've gone wrong?

https://gyazo.com/0565b8741b3035479502fc8a518b2acd

multiplication factor would be 100 % - 15% = 85%

85 % = 0.85

$a (0.85)^3 = 11054.25$

$a = \frac{11054.25}{(0.85)^3}$









$n > 8.881 ...$

What is the answer? Didn't sleep last night so a bit slow but nothing jumps out at first

You and me both, I woke up yesterday at 3pm and haven't slept since

I think the part I'm getting wrong is using





solutionbank just uses n, do you know why this is?