Question

The probability for a randomly selected number out of 1, 2, 3, 4, ..., 25 to be a composite number is :

• A. \( \frac{15}{25} \)
• B. \( \frac{10}{25} \)
• C. \( \frac{11}{25} \)
• D. \( \frac{9}{25} \)

Hint:

Always subtract both prime count and '1' from the total to get the composite count.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Count total composite numbers and divide by total numbers (25).
Step 2: Detailed Explanation:
Primes between 1-25: 2, 3, 5, 7, 11, 13, 17, 19, 23 (Total = 9).
The number '1' is neither prime nor composite.
Total non-composite numbers = \( 9 + 1 = 10 \).
Total composite numbers = \( 25 - 10 = 15 \).
Probability = \( \frac{15}{25} \).
Step 3: Final Answer:
The probability is \( \frac{15}{25} \).