A company that manufactures radios first pays a start-up cost and then spends a certain amount of money to manufacture each radio. If the cost of manufacturing radios is given by the function c(r) - 3.25r+ 225, then which description best interprets the meaning of 3. 25 in this context?
the company's start-up cost
o the profit earned from the sale of one radio
the amount spent to manufacture each radio
o the average number of radios manufactured