# Subjects for the next presidential election poll are contacted using telephone numbers in which the last four digits are randomly selected (with replacement). Find the probability that for one such phone number, the last four digits include at least one 0.

Probability
Subjects for the next presidential election poll are contacted using telephone numbers in which the last four digits are randomly selected (with replacement). Find the probability that for one such phone number, the last four digits include at least one 0.

We have $$\displaystyle{10}^{{4}}={10000}$$
numbers to choose from (on each of the 4 places we can put any of the 10 digits). Also, we have $$\displaystyle{9}^{{4}}={6561}$$
$$\displaystyle\frac{{6561}}{{10000}}={0.6561}$$