Learning curves are used in production operations to estimate the time required to complete a repetitive task as an operator gains experience. Suppose a production manager has compiled 30 time values for a particular operator as she progressed down the learning curve during the first 100 units. A portion of this data is shown in the accompanying table.

Unit NumberTime per Unit (minutes)

3................................................18.30

5................................................17.50

⋮........................................................⋮

100..............................................5.60

a. Create a scatterplot of time per unit against units built. Superimpose a linear trendline and a logarithmic trendline to determine visually the best-fitting model.

b. Estimate a simple linear regression model and a logarithmic regression model for explaining time per unit using unit number as the explanatory variable.

c. Based on R2, use the best-fitting model to predict the time that was required for the operator to build Unit 50.