00:01
In this scenario, we have 8 ,000 units being produced each year, but after each year, 10 % of the existing stock becomes inoperable.
00:16
So this should hint towards a finite geometric series.
00:22
And to find the sum of a finite geometric series, so we're going from one year to, in this case, n years, i want to use the formula a times the quantity 1 minus r to the n power all over 1 minus r.
00:41
R here is going to be my ratio.
00:46
So every year i'm losing 10 % of my products.
00:52
But that means i'm retaining 90 % of my previous year's product.
00:59
So my ratio in this case will not be 10%.
01:02
It will be 90 % or 0 .9, because the stock of each year will be 90 % of the previous year.
01:16
So let's plug in some numbers.
01:19
Well, a stands for our first term...