Economic terms: General Awareness & Current Affairs Notes for RBI Grade B

Economic Terms – RBI Grade B (General Awareness & Current Affairs)

Audience: Candidates preparing for the RBI Grade‑B exam
Style: MIT‑level, from first principles. All equations are shown, derivations are given, and edge‑cases are discussed.
Goal: Provide a compact, rigorous, and self‑contained reference that can be skimmed quickly on exam day and used for deeper study.

1. Macro‑Economic Foundations

Term	Symbol	First‑Principle Definition	Key Formula	Edge‑Case / Comment
Gross Domestic Product	(GDP)	Total market value of all final goods & services produced inside the country in a given period.	(GDP = C + I + G + (X-M)) (Consumption + Investment + Government Spending + Net Exports)	If (X-M < 0) (trade deficit) GDP still positive.
Gross National Product	(GNP)	Total value of goods & services produced by nationals (resident or non‑resident) in a given period.	(GNP = GDP + \text{Net Factor Income from Abroad})	When factor incomes are large, GNP can differ significantly from GDP.
Inflation	(\pi)	Percentage change in price level over time.	(\pi_t = \frac{P_t - P_{t-1}}{P_{t-1}})	Zero inflation → (\pi=0). Deflation → (\pi<0).
Consumer Price Index (CPI)	—	Weighted average of price changes of a basket of consumption goods.	(CPI_t = \frac{\sum_i w_i P_{i,t}}{\sum_i w_i P_{i,0}})	Basket weights (w_i) may be updated, leading to “index‑number problem.”
Producer Price Index (PPI)	—	Weighted average of price changes at the producer level.	(PPI_t = \frac{\sum_i w_i P_{i,t}^{producer}}{\sum_i w_i P_{i,0}^{producer}})	Often a leading indicator of CPI.
Unemployment Rate	(u)	Proportion of the labor force that is job‑seeking but not employed.	(u = \frac{U}{L}) where (U) = unemployed, (L) = labor force	“Underemployment” and “discouraged workers” are not captured.
Fiscal Policy	—	Government’s use of spending & taxation to influence the economy.	(G + T) (public spending + tax revenue)	Edge case: Deficit ((G > T)), Surplus ((T > G)).
Monetary Policy	—	Central bank’s manipulation of money supply & interest rates.	(M) (money supply) = (P \times Y) (M‑P‑Y model).	Stagflation (high inflation + high unemployment) forces policy trade‑offs.

2. Micro‑Economic Building Blocks

Term	Definition	Representative Model	Edge‑Case / Comment
Demand	Quantity of a good consumers are willing to buy at each price.	(Q_d = f(P)), downward sloping.	Giffen goods: demand rises when price rises due to income effect > substitution effect.
Supply	Quantity producers are willing to sell at each price.	(Q_s = g(P)), upward sloping.	Backward‑bend supply curve exists at very high prices (e.g., labor supply).
Elasticity of Demand	Responsiveness of quantity demanded to price changes.	(\varepsilon_d = \frac{dQ_d}{dP}\frac{P}{Q_d})	Elasticity > 1 → elastic; < 1 → inelastic.
Marginal Utility	Additional utility from one more unit.	(MU_x = \frac{\partial U}{\partial x})	Diminishing marginal utility: (MU_x) decreases as (x) increases.
Production Function	Relationship between inputs and output.	(Y = F(K, L, \ldots)) (Cobb–Douglas, e.g., (Y = A K^\alpha L^{1-\alpha}))	Returns to scale: increasing, constant, decreasing.
Cost Functions	Total cost, average cost, marginal cost.	(TC = VC + FC); (AC = TC/Q); (MC = \frac{dTC}{dQ})	Sunk cost is irrelevant for future decisions.
Market Structures	Perfect competition, monopolistic competition, oligopoly, monopoly.	Each has distinct demand, cost, and pricing implications.	Monopolistic competition approximates real markets with many firms but differentiated products.

3. Advanced Economic Theory

All derivations assume a closed, frictionless economy unless otherwise noted.

3.1 IS–LM Model (Macroeconomic equilibrium)

IS (Investment‑Savings): equilibrium in goods market.
[ Y = C(Y - T) + I(r) + G + (X-M) ] where (r) is the real interest rate.
LM (Liquidity‑Preference Money supply): equilibrium in money market.
[ M/P = L(r, Y) ] where (M) is nominal money supply, (P) price level.

Proof (Sketch)

Assume exogenous (M), (P).
Solve IS for