What is the probability that a randomly chosen integer from the interval (271; 342) will be divisible by 9?

The number of integers that are in the interval (271; 342) without taking into account the extreme numbers that are not included in the interval, we calculate as 341 – 270 + 1 = 72.

Starting from the number 279, every ninth number will be divisible by 9. Such numbers will be: 288, 297, 306, 315, 324, 333. There will be 6 of them.

Using the rule of classical probability, we find the probability of the event specified in the condition. It will be calculated as the ratio of the number of numbers that are divisible by 9 to the total number from the interval: 6/72 = 1/12.