13. A residential community has 100 residents who are concerned about security. The accompanying table gives the total cost of hiring a 24-hour security service as well as each individual resident’s total benefit.

Total Quantity of individual security benefit to guards Total cost each resident 0 $0 $0 1 150 10 2 300 16 3 450 18 4 600 19 Quantity Tanisha’s Ari’s of street individual individual cleanings marginal marginal per month benefit benefit 0

$10 $8 1

6 4 2

2 1 3