A number is chosen at random from 1 to 50. Find the probability of not selecting odd or prime numbers.

To solve this problem, we first need to understand what odd and prime numbers are.

1. Odd numbers are any integer that cannot be evenly divided by 2. In the range of 1 to 50, there are 25 odd numbers (1, 3, 5, ..., 49).

2. Prime numbers are numbers that have only two distinct positive divisors: 1 and the number itself. The prime numbers between 1 and 50 are: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47. There are 15 prime numbers.

However, you'll notice that some numbers are both odd and prime (all prime numbers except 2 are odd). So if we simply add the odd and prime numbers, we'll be counting some numbers twice. To avoid this, we only count the even prime number (2) separately.

So, the total number of odd or prime numbers is 25 (odd) + 1 (2 is the only even prime number) = 26.

We're asked to find the probability of not selecting these numbers. There are 50-26 = 24 numbers that are not odd or prime.

Probability is defined as the number of favorable outcomes divided by the total number of outcomes. In this case, the favorable outcomes are the 24 numbers that are not odd or prime, and the total outcomes are the 50 numbers we can choose from.

So, the probability of not selecting an odd or prime number is 24/50 = 0.48 or 48%.