Learning Curve

If you are asking how long it will take to produce an extra 3 units (given that you have already produced 1 unit) then no problem. An extra three will mean that you will have produced 4 units in total. Wrights Law (of doubling) means that we can calculate the average time per unit if we produce 4 unit - it is 81 hours. So the total time to produce 4 units is 4 x the average time per unit = 4 x 81 = 324 hours. We know that the first unit takes 100 hours, and so if 4 units takes 324 hours in total then the time for the extra three units is 324 - 100 = 224 hours. You can take the same approach for calculate the time for an extra 7 units, because having already made 1 unit it means that you will then have made 8 units in total. Again you can get the average time per unit from doubling and continue as above.

I am confusing because when i calculated the 3 units time by using formula (Y=axb) i get answers 254 hrs Y=100 x (3)^ -0.152 Y= 84.62hrs x 3 Y=254hrs and your answer is 224 hrs there is big difference why it is ??......is my answer is correct??

Well it depends whether you are trying to get the total time for the first three, or the total time for the next 3 (given that you have already produced 1). If you want the total for the next three, then what I wrote above is correct. If you want the total for the first three (including the one already made) then you have no choice but to use the formula, and what you have written is correct.

Thank u so much.

You are welcome :-)