Final answer:
To find the total net benefit (TNB) when working out for 2 hours, subtract the marginal cost of exercising for 2 hours from the sum of the marginal benefits of exercising for 2 hours.
Step-by-step explanation:
The table provided describes the marginal benefits and costs of exercising for additional hours. To find the total net benefit (TNB) when working out for 2 hours, you need to calculate the difference between the marginal benefits and the marginal costs of exercising for those 2 hours. Subtract the marginal cost of exercising for 2 hours from the sum of the marginal benefits of exercising for 2 hours to get the TNB.