Q: A consumer is indifferent between consuming 3 wireless earbuds and 2 stylus pens, or 6 wireless earbuds and 1 stylus pen per year. What is the marginal rate of substitution (MRS) between wireless earbuds and stylus pens as the consumer moves from the first to the second bundle?

$MRS = \frac{\Delta \text{wireless earbuds}}{\Delta \text{stylus pens}} = \frac{6-3}{1-2} = -3$

Question 1

Suppose a consumer is deciding how to allocate a fixed income between two goods: coffee and muffins. The price of coffee is $2 per cup and the price of muffins is $4 each. If the marginal utility of the last cup of coffee consumed is 12 utils and the marginal utility of the last muffin is 20 utils, what should the consumer do to maximize total utility?

Accepted Answer

Buy more coffee and fewer muffins, because $\frac{MU_{coffee}}{P_{coffee}} = \frac{12}{2} = 6$ and $\frac{MU_{muffin}}{P_{muffin}} = \frac{20}{4} = 5$.

Question 2

Which of the following best describes the law of diminishing marginal utility?

Accepted Answer

As more of a good is consumed, the marginal utility from each additional unit eventually decreases.

Question 3

A consumer is currently spending all of their income on two goods, A and B. The marginal utility per dollar spent on A is $8$, and on B is $10$. What should the consumer do to reach the consumer optimum?

Accepted Answer

Buy more of good B and less of good A until $\frac{MU_A}{P_A} = \frac{MU_B}{P_B}$.

Question 4

If the price of digital apps falls from $5 to $4, holding income and the price of other goods constant, what happens to the consumer's budget constraint and optimum?

Accepted Answer

The budget constraint rotates outward, allowing the consumer to reach a higher indifference curve and consume more digital apps.

Question 5

Which of the following statements about the substitution effect is correct?

Accepted Answer

It refers to the tendency of consumers to substitute a cheaper good for a relatively more expensive one.

Question 6

A consumer is indifferent between consuming 3 wireless earbuds and 2 stylus pens, or 6 wireless earbuds and 1 stylus pen per year. What is the marginal rate of substitution (MRS) between wireless earbuds and stylus pens as the consumer moves from the first to the second bundle?

Accepted Answer

$MRS = \frac{\Delta 	ext{wireless earbuds}}{\Delta 	ext{stylus pens}} = \frac{6-3}{1-2} = -3$

Question 7

Which of the following best explains the diamond-water paradox?

Accepted Answer

Water is cheaper than diamonds because its marginal utility is lower, despite its higher total utility.

Question 8

Suppose a consumer's budget is $30, wireless earbuds cost $5 each, and stylus pens cost $10 each. What is the equation for the budget constraint?

Accepted Answer

$5Q_{earbuds} + 10Q_{pens} = 30$

Question 9

Which of the following is NOT an assumption required for the law of diminishing marginal utility to hold?

Accepted Answer

Consumers must always behave irrationally.

Question 10

A consumer is at a point where the indifference curve is tangent to the budget constraint. What does this point represent?

Accepted Answer

The consumer is maximizing total utility given their budget.

Question 11

If a consumer experiences bounded rationality, which of the following is most likely to occur?

Accepted Answer

The consumer may make suboptimal choices due to limited information or cognitive limitations.

Question 12

If the price of stylus pens decreases from $10 to $5, what happens to the consumer's demand for stylus pens, all else equal?

Accepted Answer

The quantity demanded increases, as shown by a movement along the demand curve.

Question 13

Which of the following statements about indifference curves is correct?

Accepted Answer

Indifference curves are convex to the origin, reflecting a diminishing marginal rate of substitution.

Question 14

A consumer spends all their income on two goods, X and Y. At the optimum, which of the following must be true?

Accepted Answer

$\frac{MU_X}{P_X} = \frac{MU_Y}{P_Y}$

Question 15

Which of the following is an example of the real-income effect?

Accepted Answer

A consumer buys more of a good because its price falls, increasing their effective purchasing power.

Question 16

Suppose a consumer is choosing between two bundles: Bundle A (4 wireless earbuds, 2 stylus pens) and Bundle B (2 wireless earbuds, 4 stylus pens). If both bundles lie on the same indifference curve, what does this imply?

Accepted Answer

The consumer derives the same total utility from both bundles.

Question 17

If a consumer's marginal utility from the last dollar spent on designer shoes is equal to the marginal utility from the last dollar spent on groceries, what does this indicate?

Accepted Answer

The consumer is maximizing total utility given their budget.

Question 18

Which of the following is a limitation of the law of diminishing marginal utility?

Accepted Answer

It may not apply to rare collectibles, where additional units can increase marginal utility.

Question 19

A consumer is considering whether to buy a $1,650 Canada Goose jacket and a $90,000 sports car on the same day. According to utility theory, under what condition would this be rational?

Accepted Answer

If the marginal utility per dollar spent on each item is equalized and the consumer can afford both.

Question 20

Which of the following best describes the effect of a new, complex digital system in a car on marginal utility per dollar spent for some consumers?

Accepted Answer

It may lower the marginal utility per dollar spent if the system is difficult to use or unreliable.

Consumer Choice: Utility, Optimization, and Behavioural Insights

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