You have described the 'First In First Out' and 'Weighted Average' method of costing your purchases. Both methods can correct, depending on what you are trying to achieve. If you have no specific intent in mind, this is slightly subjective.
For tax purposes, some countries allow or require you to use FIFO, and some allow or require you to use a weighted ...
Basically there are two way you can calculate return of your investment
ROI= Net Return on Investment / Cost of Investment × 100%
ROI= Final Value of Investment − Initial Value of Investment / Cost of Investment × 100%
Assume an investor bought 10000 shares of the some company. at $100 per share. One year later, the investor sold the ...