Which categories of goods used by ordinary people are most affected by scarcity? Use examples from two of these categories and explain how the scarcity of these goods might arise and how this scarcity would affect most people.

Categories of goods include non durable goods and consumer goods

Explanation:

Goods required and needed by ordinary people are mostly non-durable goods or consumer goods. These are perishable goods that don't last and are needed regularly such as food and clothes. If for instance there is drought, consumer goods such as rice or tomatoes become hard to grow and therefore become scarce. Also if there is an extreme economic problem brought about by war or natural human disasters like storms, capital for production of food or clothes become lacking therefore consumer goods or non-durable goods get scarce

answer: marginal utility of the fourth brownie is 0.

explanation: marginal utility is the addtional utility gained from the consumption of one more unit of a good. it is given by,

so, marginal utility at the 4th unit will be given by

since, the values are not given here, you can simply find marginal utility at fourth unit by subtracting total utility at 3rd unit from total utility at 4th unit.