This table presents the cost-benefit ratios of four levels of interventions/targets to achieve improved access to water supply and sanitation for seven different regions of the world. For example, the total global economic benefits for reaching the MDG target accrue to $84 billion.

2a. Explain how the cost-benefit ratio differs from the cost effectiveness ratio and why the costbenefit ratio is more appropriate here than the cost-effectiveness ratio. (5 points)

2b. State numerically (and show calculations) for how the cost-benefit ratio for intervention 4 Access for all to regulated in-house piped water - for Africa is calculated (Hint: all the information you need is in the table). (4 points)

2c. State two types of benefits and two types of costs that the researchers would have included in their analysis. (4 points)

2d. Suppose all the benefits were calculated using outcomes from RCTs. These RCTs were all testing one package of interventions: the provision of small scale water supply technologies; and hygiene awareness and promotion. Based on the table below, do you think that the result that this package of interventions improved access to water supply and sanitation is generalizable? Why or why not? (4 points)