14. A residential community has 100 residents who are concerned about security. This table gives the total cost of hiring a 24-hour security service as well as each individual resident’s total benefit.
| Quantity of security guards |
Total cost | Total individual benefit to each resident |
| 0 | $0 | $0 |
| 1 | 150 | 10 |
| 2 | 300 | 16 |
| 3 | 450 | 18 |
| 4 | 600 | 19 |
Explain why the security service is a public good for the residents of the community.
Calculate the marginal cost, the individual marginal benefit for each resident, and the marginal social benefit.
If an individual resident were to decide about hiring and paying for security guards on his or her own, how many guards would that resident hire?
If the residents act together, how many security guards will they hire?