A sewage treatment plant has three possible schemes of sewage carriage and treatment systems. If the life of the scheme is 20 years, which scheme should be recommended as the most economic?

Scheme Installation Cost (`) Annual Running Cost (`)

A 18,250,000 7,250,000 B 20,200,000 4, 600,000 C 24,200,000 4,000,000 Use 15% to represent the cost of capital. If the cost of capital were 10%, would the recommendation alter?