Svalbardi, a water sourced from Norwegian icebergs that are up to 4,000 years old, sells for $99 a bottle. From extreme luxury to the ordinary, the market for bottled water is growing quickly as people switch from soft drinks and alcohol to healthier alternatives. Market researchers report that consumption of bottled water overtook that of sugary soft drinks in America in 2016.

a. Assuming that the price of an ordinary bottle of water is $1, what can we infer about the marginal utility of a bottle of ordinary water and the marginal utility of a bottle of Svalbardi for a person who buys one bottle of Svalbardi and 100 bottles of ordinary water per year?

b. Why might the marginal utility from a bottle of Svalbardi decrease more rapidly than the marginal utility from ordinary bottled water?