Randomly open a 342page book and mark a page What is the pro

Randomly open a 342-page book, and mark a page. What is the probability that the number of the page contains the lucky number 5?

Solution

we have from 0--> 100   there are 20 numbers that contains a number 5

from 101 to 200 there are 20 numbers that contains number 5

and from 301 to 342 there are 4 numbers that cointain number 5

so the probability is [20+20+4 ] / 342 = 0.1286