Lagoon Hotels Limited pays its electricity bill based on a fixed standing charge of ₦150,000 per month plus ₦85 per kilowatt-hour consumed. This cost is BEST described as:

A semi-variable (mixed) cost contains both a fixed element and a variable element. The standing charge of ₦150,000 is the fixed component that is incurred regardless of consumption, while the ₦85 per kilowatt-hour is the variable component that changes with the level of activity. This dual nature classifies the electricity bill as semi-variable.