The marginal utility of the third Pepsi is 8 units of utility
Explanation:
Marginal utility attempts to measure the additionally fulfilled use of extra products or services by a customer.
Economists use the idea of marginal demand to assess how much a individual good is likely to pay.
The complete utility of that first two Pepsi is equal to 30(= 18 + 12).
Thus, the marginal value of the third Pepsi is equal to 8 (= 38-30).