Question

The demand function of a commodity x is given by Q_x = 20 − 3P_x. Find out the values of P_x when corresponding values of Q_x are given as: 5, 8, 11 and 14.

Answer 1

Rearrange the demand function to find price: \[ P_x = \frac{20-Q_x}{3} \]

Quantity demanded (Qx)	Price (Px)
5	₹ 5
8	₹ 4
11	₹ 3
14	₹ 2

\[ \begin{aligned} Q_x=5:\quad &P_x=\frac{20-5}{3}=₹5\\[6pt] Q_x=8:\quad &P_x=\frac{20-8}{3}=₹4\\[6pt] Q_x=11:\quad &P_x=\frac{20-11}{3}=₹3\\[6pt] Q_x=14:\quad &P_x=\frac{20-14}{3}=₹2 \end{aligned} \]