Question 8:

A certain calculating machine uses only the digits 0 and 1. It is supposed to transmit one of these digits through several stages. However, at every stage, there is a probability p that the digit that enters this stage will be changed when it leaves and a probability q = 1 - p that it won’t. Form a Markov chain to represent the process of transmission by taking as states the digits 0 and 1. What is the matrix of transition probabilities?

Given the outline of this problem there are only four possibilities for how the calculating machine can act.

  1. 0 –> 1
  2. 0 –> 0
  3. 1 –> 1
  4. 1 –> 0

There are also only two states:

  1. 0
  2. 1

So, the matrix of transition probabilities will look like this:

\[\begin{bmatrix} q & p \\ p & q \end{bmatrix}\] Or, when substituting for q: \[\begin{bmatrix} p - 1 & p \\ p & p - 1 \end{bmatrix}\]