In the application presented in this section, one of Jacob Mincer's specifications relating earnings to schooling(S) and workplace experience(X) is In E = 4.9 + 0.26lnS - 0.003lnS2- 0.004lnXS + 0.15lnX - 0.002lnX2.
A) What is the partial derivative of the logarithm of earnings with respect to experience?
B) What is the percentage impact on earnings due to a one year increase in experience if S = 20 and X = 5?