A cellular telephone bill when a flat fee is charged for the first 500 minutes of use per month and additional use costs $0.25 per minute Answer b. Total selling and administrative costs Answer c. Total labor costs when employees are paid per unit produced Answer d. Total overtime premium paid production employees Answer e. Average total cost per unit Answer f. Salaries of supervisors when each one can supervise a maximum of 10 employees Answer g. Total idle time costs when employee are paid for a minimum 40-hour week Answer h. Materials costs per unit Answer i. Total sales commissions. Answer j. Electric power consumption in a restaurant Answer k. Total costs when high volumes of production require the use of overtime and obsolete equipment Answer l. A good linear approximation of actual costs Answer m. A linear cost estimation valid only within the relevant range