Learning rate

Dear Sir,

Could you please help?

A manufacturing company wants to measure the learning rate that it has achieved with the manufacture of a new product item. The first item produced took 6 hours to make and the average time for the first 16 units was 3.3 hours.

What has been the learning rate for this product to nearest 1?

Answer
86%

3.3/6 r4 =0.55
r 0.861 therefore 86.1%

I used the equation
3.3= 6x(16r4)
0.557/16
r4 0.034375 0.43 43%

Which one is the correct?

thanks

Gabriella