1. What is the difference between variable and fixed costs?

Also explain how the total variable cost and total fixed cost is affected by increasing the number of units produced? What happens to the total variable cost per unit and total fixed cost per unit?

2. What is a mixed cost?

3. The high-low method of analyzing mixed costs uses only two observation points: the high and low points of activity. Are these always the best points for prediction purposes? Why or why not?

Please answer it more than 3 sentences and reference.