Cardinal uses the high-low method of estimating costs. Cardinal had total costs of $26,410 at its lowest level of activity, when 10,000 units were sold. When, at its highest level of activity, sales equaled 15,900 units, total costs were $39,390. Cardinal would estimate variable cost per unit as:

1. which one of the following would be an example of a supply-side market failure? a. a gas station is slowly leaking diesel fuel from its underground tanks, and after the leak is discovered, the business immediately cleans up the pollution at its own expense. b. a gas station is slowly leaking diesel fuel from its underground tanks, but the state uses taxpayer money to clean up the pollution rather than requiring the business to pay. c. your business wants to attract repeat customers by putting on a customer-appreciation picnic at a public park, but you decide not to because you couldn't prevent noncustomers from consuming the food and entertainment you provided. d. everyone rushes to the local retail outlet at midnight on the day of the release of a new video game console, and the store runs out before everyone is able to buy one.