1.The signal x(n) = x(n+20) said to be periodic with period: 

a.50

b.70

c.10

d.40

e .30

2.The z-transform of x(n) = 10 sequence is

a.X(z) = 10*u(n)

b.X(z) = 10*n

c.X(z) = 10

d.X(z) = 10*10

e.None of above

3.If the signal x(t)=4cos250πt+2sin500πt-cos100π2t, then the optimal sampling rate is: 

a.More than or equal to 250 Hz

b.More than or equal to 500 Hz

c.Less than or equal to 250 Hz

d.Less than or equal to 500 Hz

e.None of above