Using the data in the table above, with y measured on the vertical axis, the slope of the line relating y to x is

If the errors are heteroskedastic, then

A) the OLS estimator is still BLUE as long as the regressors are nonrandom. B) the usual formula cannot be used for the OLS estimator. C) your model becomes overidentified. D) the OLS estimator is not BLUE.

Diana is a personal trainer whose client Charles pays $80 per hour-long session. Charles values this service at $100 per hour, while the opportunity cost of Diana's time is $75 per hour. The government places a tax of $10 per hour on personal trainers. Before the tax, what is the total surplus?

a. $25 b. $20 c. $5 d. $0