Question

Difficulty: HardLaw of Diminishing Marginal Utility

The table below presents the utility schedule of a consumer consuming successive portions of roasted maize:

Quantity (QQ)Total Utility (TUTU) in utilsMarginal Utility (MUMU) in utils
11818
23416
3PP12
454QmQ_m
5584
6580
752-6

Based on the table, what is the combined value of P+QmP + Q_m, and at which unit of consumption does the consumer reach the point of satiety?

  1. 5454 utils and the 6th unitAnswer
  2. B
    5454 utils and the 5th unit
  3. C
    5050 utils and the 6th unit
  4. D
    5858 utils and the 7th unit

Answer

The combined value of P+QmP + Q_m is 5454 utils, and the point of satiety is reached at the 6th unit.
To find PP, add the marginal utility of the 3rd unit (1212) to the total utility of the 2nd unit (3434), yielding P=46P = 46. To find QmQ_m, subtract the total utility of the 3rd unit (4646) from the total utility of the 4th unit (5454), yielding Qm=8Q_m = 8. Summing these gives 46+8=5446 + 8 = 54 utils. The point of satiety is the quantity at which marginal utility is zero (MU=0MU = 0), which occurs at the 6th unit where total utility peaks at 5858 utils.

Step-by-Step Solution

1
Calculate the unknown Total Utility PP at the 3rd unit.
P=TU2+MU3=34+12=46P = TU_2 + MU_3 = 34 + 12 = 46 utils.
Total utility at quantity QQ equals total utility at Q1Q-1 plus marginal utility at QQ.
2
Calculate the unknown Marginal Utility QmQ_m at the 4th unit.
Qm=TU4TU3=5446=8Q_m = TU_4 - TU_3 = 54 - 46 = 8 utils.
Marginal utility at quantity QQ is the change in total utility resulting from consuming that unit.
3
Sum PP and QmQ_m.
P+Qm=46+8=54P + Q_m = 46 + 8 = 54 utils.
Simple addition of the calculated values.
4
Identify the point of satiety.
The 6th unit.
The point of satiety (maximum total satisfaction) occurs at the consumption level where Marginal Utility equals zero (MU=0MU = 0) and Total Utility reaches its maximum.

Key Concept

Law of Diminishing Marginal Utility and Relationship between Total Utility and Marginal Utility
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