Which of the following statements are correct?
(A) In a demand function, price is the dependent variable.
(B) The graph of y = 5 + x slopes downward.
(C) The graph of a decreasing function slopes downward.
(D) The demand curve is drawn with price, the independent variable, on the vertical axis.
(E) In a graph, the independent variable is usually measured along the horizontal axis.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → (C), (D) and (E) only
In a function, the independent variable decides the value of the dependent one. For a demand function, price is independent and quantity depends on it.
(A) In a demand function, price is the dependent variable. — Incorrect. Quantity depends on price, so price is the independent variable.
(B) The graph of y = 5 + x slopes downward. — Incorrect. y rises as x rises, so the graph slopes upward.
(C) The graph of a decreasing function slopes downward. — Correct. y falls as x rises, so the line goes down.
(D) The demand curve is drawn with price, the independent variable, on the vertical axis. — Correct. Economics often swaps the usual axes for the demand curve.
(E) In a graph, the independent variable is usually measured along the horizontal axis. — Correct. This is the usual way of drawing a graph.
NCERT (2026-27): “Graphical Representation of a Function … Usually, in a graph, the independent variable is measured along the horizontal axis and the dependent variable is measured along the vertical axis. However, in economics, often the opposite is done. The demand curve, for example, is drawn by taking the independent variable (price) along the vertical axis and the dependent variable (quantity) along the horizontal axis. The graph of an increasing function is upward sloping or and the graph of a decreasing function is downward sloping. As we can see from the diagrams above, the graph of y = 5 + x is upward sloping and that of y = 50 – x, is downward sloping.” |