An Appliance Store Manager Estimates That for X Television Ads $R ( x ) = - 0.01 x ^ { 3 } + x ^ { 2 } - 3 x + 200$

Multiple Choice

An appliance store manager estimates that for x television ads run per day, $R ( x ) = - 0.01 x ^ { 3 } + x ^ { 2 } - 3 x + 200$ refrigerators will be sold per month. Find $R ^ { \prime } ( 4 )$ and interpret what it tells us about sales.

A) $R ^ { \prime } ( 4 ) = 203.36$ they'll sell about 203 refrigerators if they run 4 ads per day.
B) $R ^ { \prime } ( 4 ) = 4.52$ they'll sell about 5 refrigerators if they run 4 ads per day.
C) $R ^ { \prime } ( 4 ) = 4.52$ sales will be increasing at about 5 refrigerators per month per ad when they're running 4 ads.
D) $R ^ { \prime } ( 4 ) = 203.36$ the cost of refrigerators will be rising by $203.36 if they're selling 4 per day.