Question

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.

Answer 1

Answer:.344 if you have to round to the third decimal

Explanation:

Answer 2

The complementary event of that the last four digits include at least one 0 is that the last four digits do not include any 0. So, for the first digit, there are 9 ways to pick a digit from 1 to 9. Similarly, there are 9 ways to pick each of other digits. Then the probability that a 4-digit numbers that do not include 0 is chosen is (9*9*9*9)/10^4 = 0.6561. So the probability that the last four digits include at least one 0 is 1 – 0.6561 = 0.3439