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Marlow Works

AP Macroeconomics / Financial Sector

Lesson

Monetary policy and loanable funds

Rate changes travel to investment. Saving and borrowing meet in another graph.

Learning goals

  • Trace easier money from lower rates to AD.
  • Shift loanable funds for saving, investment demand, or public borrowing.

Explanation

Lower nominal rates, other things equal, make interest-sensitive spending more attractive. Investment rises, AD shifts right, and short-run output and prices can rise. Tighter money does the reverse. Lags and confidence can blunt the path; the model still gives you the intended direction.

The loanable-funds market uses a real interest rate. Savers supply funds; borrowers demand them. A government deficit can increase public borrowing, shift demand for funds right, and raise the real rate—the crowding-out channel again. Capital inflows from abroad can add supply and ease that pressure.

Key terms

  • Monetary policy. Central-bank actions that change the money supply or interest rates to influence spending.
  • Loanable funds. The market in which savers supply and borrowers demand funds at a real interest rate.

Common mistakes

  • Putting the nominal rate on a loanable-funds graph.
  • Claiming monetary policy shifts LRAS in the short-run classroom model.

Practice

Original Marlow Works items. Check the answer explanation after you try.

1 of 2Economic Indicators and the Business Cycle · easy · multiple choice

Nominal GDP rises from one year to the next while real GDP is unchanged. Which interpretation is best?

Original Marlow Works item — not a College Board question.

Take your time—this is practice, not a test.

Answer explanation

Households save more at every real interest rate. What happens to the real rate and investment, other things equal?

Answer. Supply of funds shifts right, the real rate falls, and equilibrium investment rises.

Cheaper real borrowing encourages more interest-sensitive spending.

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Related resources

External links with reuse status. Marlow Works is independent and does not copy restricted exam or textbook material.

  • Official / link only

    AP Macroeconomics course page

    Official six-unit framework for national income and policy models.

    College Board · All rights reserved · accessed 2026-10-01

    Open source

  • Official / link only

    FRED economic data

    Federal Reserve economic data. Terms vary by series; do not scrape or ingest.

    Federal Reserve Bank of St. Louis · Varies by series · accessed 2026-10-01

    Open source