A Mall Kiosk Sells Two Different Models of Pagers, the Elite

Multiple Choice

A mall kiosk sells two different models of pagers, the Elite and the Diamond. Their monthly profit from pager sales is $P ( x , y ) = ( x - 40 ) ( 20 - 5 x + 6 y ) + ( y - 50 ) ( 30 + 3 x - 4 y )$ where x and y are the prices of the Elite and the Diamond respectively, in dollars. At the moment, the Elite sells for $32 and the Diamond sells for $40. Use calculus to estimate the change in monthly profit if the kiosk operator raises the price of the Elite to $33 and lowers the price of the Diamond to $38.

A) Profit will increase by about $26.
B) Profit will decrease by about $310.
C) Profit will increase by about $194.
D) Profit will stay the same.