2. (8 marks)An industry has perfect competitive market in both labor market and output market. Assume there are many identical small firms in the industry. Why is industry labor demand curve steeper than the sum of labor demand curve of each firm in the industry? Explain with proper figures.

3. (13.5 marks) The demand for big data engineer increased shapely in recent years, and the training of these engineers needs a few years. List the two assumptions of Cobweb Model, and use the model to explain that the entry level salary of big data engineer is likely to be unstable across different years.