According to 2014 data on the U.S. population, which of the following groups of adults of prime working age (ages 25-54) had the highest labor-force participation rate?

A consumer has $20 that he wants to spend on two goods: pens priced at $2 each, and pencils priced at $1 each. Which of the following correctly represents his budget constraint?

A) $20 = ($2/Quantity of pens) + ($1/Quantity of pencils) B) $20 = ($2 × Quantity of pens) + ($1 × Quantity of pencils) C) $20 = ($3/Quantity of pens + Quantity of pencils) D) $20 = $3 × (Quantity of pens - Quantity of pencils)

The benefit from an additional unit of a good or service that the consumer of that good or service receives is the

A) marginal private benefit. B) marginal external benefit. C) marginal social benefit. D) opportunity cost.