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. The supply and demand for wheat are given by QS = 20 + 100p QD = 4000 - 100p +

ID: 1136038 • Letter: #

Question

. The supply and demand for wheat are given by QS = 20 + 100p QD = 4000 - 100p +10Y Where Y is the average consumer income.

a. Compute the partial derivative of quantity demand with respect to changes in average consumer income. dQD/dA = 10

b. Solve for the equilibrium price and quantity as functions of the consumer income.

QS = QD: 20 + 100p = 4000 – 100p + 10Y 200p = 3980 + 10Y p*(Y) = 19.9 + 0.05Y Q*(Y) = 2010 + 5Y

c. Compute the derivatives of the equilibrium price and quantity with respect to income. dp*/dY = 1/20 dQ*/dY = 5

These are the questions and answers, I just need a very detailed explanation for each step because I do not seem to understand how we get those answers.

Explanation / Answer

(a) Qd = 4000- 100p +10Y

Partial derivative of Qd with respect to average consumer income is that dervative of Qd with respect to Y when all other variables are constant.

dQd/dY =10

(b) Qs = 20+100p

Qd= 4000-100p+10Y

To find equilibrium price and quantity, Equate Qd and Qs , we get:

20+100p= 4000- 100p+ 10Y

100p+100p= 4000-20 +10Y

200p = 3980 +10Y

p= (3980+10Y)/200

p*(Y)= 19.9 + 0.05Y (Equilibrium price )

Put p= 19.9+ 0.05Y in any of quantity equation , we get:

Q= 20+ 100(19.9 +0.05Y)

Q= 20+ 1990 +5Y

Q* = 2010 +5Y (Equilibrium quantity)

(c) Equilibrium price : p*=19.9 +0.05Y

Derivative of the equilibrium price with respect to income is:

dp*/dY = 0.05 = 5/100 =1/20

Equilibrium quantity : Q*= 2010+5Y

Derivative of quantity with respect to income is:

dQ*/dY = 5