Neco 2020 Data Processing Question 1

A small business wants to reduce its overall security risk by at least 70\% (i.e., the remaining risk must be at most 30\% of the original). It can implement the following security measures, each with a fixed cost and a risk‑reduction factor that multiplies the remaining risk:\n\n- Firewall: cost ₦200, reduces risk by 30\% (remaining factor 0.70)\n- Antivirus software: cost ₦150, reduces risk by 20\% (remaining factor 0.80)\n- Employee security training: cost ₦100, reduces risk by 25\% (remaining factor 0.75)\n- Data encryption: cost ₦180, reduces risk by 35\% (remaining factor 0.65)\n\nThe business may choose any combination of these measures. What is the minimum total cost that will achieve the required risk reduction, and which measures must be selected?