What is the probability that the last digit of a randomly dialed number is 5 or a multiple of 3?

Event A – an event that consists in the fact that the last digit is equal to 5 or a multiple of 3.

The number of outcomes that favor this event m = 1 + 3 = 4 (equal to 5 – one, multiple of three – 3), and the number of possible outcomes of the event in total, according to the condition of the problem, will be n = 10. Using the formula (or definition) of the classical probability, the probability of event A can be found as the ratio of the number of favorable outcomes to the total number of possible outcomes.

We get the following expression:

P (A) = m / n = 4/10 = 0.4.

Answer: 0.4.