Question

in a book of 300 pages if a page is opened at random find the probability that the sum of the digits in its number is 10​

Answer 1

Answer:

7/5

Step-by-step explanation:

Assuming that by “at random” you are talking about a uniform distribution:

We just need to examine the number of pages that meet the condition.

For single digit page numbers, none meet the condition, because the highest would be 9.

For double digit page numbers, 9 meet the condition: 19, 28, 37, … , 82, 91

For 3 digit page numbers that start with a 1, 10 meet the condition: 109, 118, 127, … , 181, 190.

For 3 digit page numbers that start with a 2, 9 meet the condition: 208, 217, 226, … , 271, 280. It is impossible for any numbers after that point because they all add up to larger numbers than 10.

The number 300 does not meet the condition.

Therefore, the number that meet the condition are: 9 + 10 + 9 = 28

That makes the probability  28/300=7/5