To find the probability that a randomly chosen number from 1 to 100 is a two-digit number, follow these steps:

1. Determine the total possible outcomes:
   The total number of numbers between 1 and 100 (inclusive) is 100.

2. Determine the number of favorable outcomes:
   A two-digit number is any number from 10 to 99.
   So, the number of two-digit numbers is $99 - 10 + 1 = 90$.

3. Calculate the probability:
   The probability $P$ of choosing a two-digit number is the ratio of favorable outcomes to total outcomes: $P = \frac{\text{favorable outcomes}}{\text{total outcomes}} = \frac{90}{100} = 0.9$ Therefore, the probability of choosing a two-digit number is $0.9$, or 90%.

Final Answer:

The probability is 0.9 (or 90%).

Would you like further clarification or details on this? Here are 5 related questions:

1. What is the probability of selecting a number between 1 and 50 that is a two-digit number?
2. How do you calculate the probability of selecting a prime number from 1 to 100?
3. What is the probability of selecting a number divisible by 3 between 1 and 100?
4. How many three-digit numbers are there between 1 and 1000?
5. How would the probability change if we considered numbers from 1 to 150?

Tip: Always check the total number of favorable outcomes carefully when solving probability problems.