Neco Model Questions Vol1 2017 Commerce Question 49

A company plans a television advertising campaign targeting 2 million viewers. The campaign aims for a Gross Rating Point (GRP) of 120. Each 30‑second spot initially reaches \(4\%\) of the target audience, but after every 10 spots the rating per spot falls by \(0.5\%\) (i.e., spots 1‑10 rate \(4\%\), spots 11‑20 rate \(3.5\%\), spots 21‑30 rate \(3\%\), and any further spots rate \(2.5\%\)). The cost of a spot is ₦150,000. The broadcaster offers a volume discount: if more than 50 spots are bought, the cost per spot is reduced by \(12\%\); if more than 80 spots are bought, the reduction is \(20\%\) (the higher discount replaces the lower). Additionally, a rebate of ₦200,000 is granted if the total GRP exceeds 130. Determine (a) the minimum number of spots required to achieve at least 120 GRP, (b) the discount rate that will apply to the chosen plan, and (c) the total cost after applying any discount and rebate.