You decrease your product price by $10 in market A but leave it unchanged in market B. Sales in A rise from 840 units per week to 940 while sales in B also rise from 770 to 790 . The difference-in-difference estimate of the effect of the price change is:

David's firm experiences diminishing marginal product for all ranges of inputs. The total cost curve associated with David's firm

a. gets flatter as output increases. b. gets steeper as output increases. c. is constant for all ranges of output. d. is unrelated to the production function.

What two key assumptions does the quantity theory make concerning variables in the equation of exchange?