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2026 PEA Q26

An economy has one good produced one-for-one from labour. The representative consumer has U ⁣(C,MP)=34lnC+14ln ⁣MPU\!\left(C, \tfrac{M}{P}\right) = \tfrac{3}{4}\ln C + \tfrac{1}{4}\ln\!\tfrac{M}{P}, labour endowment 5050, money endowment Mˉ=100\bar M = 100, with constant money supply M=MˉM = \bar M. If the price is flexible (so labour is fully employed), the equilibrium price is

Reveal answer and solution

Answer

C

Solution

  1. 1

    With linear technology and perfect competition P=WP = W. The consumer's real

  2. 2

    wealth (measured in units of the good) is

  3. 3
    Ω=L+MˉP, \Omega = L + \frac{\bar M}{P},
  4. 4

    where LL is labour supplied. Cobb--Douglas preferences imply

  5. 5
    C=34Ω,MP=14Ω. C = \tfrac{3}{4}\,\Omega, \qquad \tfrac{M}{P} = \tfrac{1}{4}\,\Omega.
  6. 6

    Full employment means L=50L = 50 and goods-market clearing C=Y=L=50C = Y = L = 50:

  7. 7
    50=34 ⁣(50+100P)    200350=100P3443. 50 = \tfrac{3}{4}\!\left(50 + \tfrac{100}{P}\right) \;\Longleftrightarrow\; \tfrac{200}{3} - 50 = \tfrac{100}{P}\cdot \tfrac{3}{4}\cdot\tfrac{4}{3}.
  8. 8

    Equivalently, the money-market condition

  9. 9
    100P=14 ⁣(50+100P) \frac{100}{P} = \tfrac{1}{4}\!\left(50 + \tfrac{100}{P}\right)
  10. 10

    gives

  11. 11
    400P100P=50    300P=50    P=6. \frac{400}{P} - \frac{100}{P} = 50 \;\Longrightarrow\; \frac{300}{P} = 50 \;\Longrightarrow\; P = 6.

Answer structure / marking notes

Either the goods market or the money market suffices (Walras' law guarantees the other clears).

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Content note

Imported from public/resources/isi/msqe/solutions/pea/2026/ISI_MSQE_PEA_2026_Solutions.tex. Question wording is retained from the available local TeX source; incomplete option blocks or ambiguous source status are flagged for review.