A dance competition on television had five elimination rounds. After each elimination, only one-fourth of the contestants were sent to the next round. The table below shows the number of contestants in each round of the competition: x 1 2 3 4 5

f(x) 512 128 32 8 2

Compute the average rate of change of f(x) from x = 2 to x = 4, and describe what it represents.