The "natural" rate of unemployment is the unemployment rate toward which the economy gravitates in the a. short run, and the natural rate is not necessarily the socially optimal rate of unemployment. b. long run, and the natural rate is the socially optimal rate of unemployment. c. long run, and the natural rate is not necessarily the socially optimal rate of unemployment. d. short run, and the natural rate is the socially optimal rate of unemployment.

The "natural" rate of unemployment is the unemployment rate toward which the economy gravitates in the long run, and the natural rate is not necessarily the socially optimal rate of unemployment. The natural rate of unemployment exists when the labor and markets are at an equilibrium. Although in theory having them equal seems like the best option for the economy, it is good to have some wiggle room in labor and available jobs. 

4.71

Explanation:

Cash coverage is a financial tool to calculate the proportion of available cash to interest expenses. It is useful in that it gives a deeper insight into available cash to offset interest expense and guide towards proper investment of cash.

Workings

Cash coverage ratio = cash + cash equivalent / interest expenses.

To arrive at the cash equivalent , depreciation is added back to the net income

Cash equivalent = 15,585+ 2,525 = 18,110

Interest expenses = 3,846

Cash coverage ratio = 18,110 / 3,846 = 4.71

This seems high and it is advisable that cash should be used for some short term investments to earn other profit