learning curve examples

You have explained two examples in your lecture on learning curve (part 2). But I asked you this specifically to know whether I understand them completely or not. For example 1: The average time taken by each unit. First unit-----= 80 hours Second unit = 55 hours What is the learning rate? Output units----Avg hour per unit-----Total hours -------1-----------------80 hrs (r)-------------80 hrs -------2--------------67.5 hrs (r)^1---------135 hrs Since first unit takes 80 hours per unit and second unit takes 55 hours but in total time the two units take (80 + 55) = 135 hours. learning rate (r) = 67.5 / 80 = 84.375% For example 2: The average time taken by each unit. First unit = 100 hours Fourth unit = 50 hours What is the learning rate? Output units-----Avg hour per unit------Total hours --------1--------------100 hrs (r)-------------100 hrs --------2--------------------hrs (r)^1----------------hrs --------4----------------50 hrs (r)^2----------200 hrs Since first unit takes 80 hours per unit and second unit takes 55 hours but in total time the two units take (80 + 55) = 135 hours. learning rate (r) = (50 / 100)^1/2 = 70.7% learning rate (r) = ^2?(50 / 100) = 70.7% Both of these approaches give the same answer of 70.7%. Is that all correct what I have written above? Thanks for your patience