Some MCQs

[RS]

I've some ques. Please answer with logic/reason/solution.

1. The number of students at a university increases from 2500 to 5000 in 10years. Based on geometric mean, the University grew at an average percentage rate of.
A. 2500 students per year
B. 1.071 % per yr
C.  7.1% per yr
D. 10% per yr

2. For what kind of preferences will a consumer be equally well off facing either quantity tax or an income tax?
A. U=x+y
B.  U=min(x,y)
C.  U=x^1/2y^1/2
D.  None of above

3. In an economy, the value of high powered money is 200 units and the money multiplier Is 5. If the demand for money Is M=1200-50i then what would be the equilibrium rate of interest?
A. 2.5
B. 4
C. 4.5
D. 6
 
4. Given percentage change in nominal GNP=1.8, percentage change in population = 0.5, percentage change in price level = 1.3, what is the approximate change in real per capita GNP?
A.  ZERO
B.  0.5
C. 1.0
D. 1.3

5. A monopolist faces a demand curve Q=20/p, the MR curve is given by
A. MR(p) = - 10/p^2
B. MR(Q) = - 10/Q^2
C.  Q=0
D. p=0

[tanudas]

Is it d for the fourth one ?

[hoouin]

for second answer is B)
since it is utility curve for perfect complement we can show it by slutsky eqn .by taking price tax as dx/dp and income tax as dx/dI (income effect) and substitution effect is 0 in perfect complement case.

for 5th answer is D) but i m not sure
what i have done is TR =20 (area under  this  rectangular hyperbola is constant) hence MR=0 (constant ).
in perfect competition we do P=MR hence P=0 . guys correct me if i m wrong