The First Unit of a Product Took 50 Hours to Build

Multiple Choice

The first unit of a product took 50 hours to build, and the learning curve is 85%. How long will it take to make the 10th unit? (Use at least three decimals in the exponent if you use the logarithmic approach.)

A) less than 24 hours
B) from 25 to 30 hours
C) from 30 to 35 hours
D) from 35 to 40 hours
E) more than 40 hours