5. The figure below shows the ACFs for 36 random numbers, 360 random numbers and 1,000 random numbers.

Explain the differences among these figures. Do they all indicate that the data are white noise?

1.0- 1.0- 1.0- 0.5 - 0.5- 0.5- 0.0 4 500=12E 300 == -0.5 - -0.5 - -0.5 - -1.0 - -1.0 - -1.0 - UN- 20 20 15 20 10 15 lag (1) 10 15 lag (1) 10 lag (1) 1.0- 1.0- 1.0- 0.5 - 0.5- 0.5- 0.0 4 500=12E 300 == -0.5 - -0.5 - -0.5 - -1.0 - -1.0 - -1.0 - UN- 20 20 15 20 10 15 lag (1) 10 15 lag (1) 10 lag (1)