Question

A box contains 20 balls bearing numbers 1, 2, 3, 4, ..., 20. A ball is drawn at random from the box. What is the probability that the number on the ball is an odd number?

Answer 1

Given: A box contains balls numbered 1 through 20; one ball is drawn at random.

Step-wise calculation:

1. Total number of possible outcomes (sample space) = 20.

2. Number of favourable outcomes (odd numbers among 1...20) = 1, 3, 5,...,19 → 10 numbers.

3. Probability = `"Number of favourable outcomes"/"Total number of outcomes"`

Hence, P(odd) = `10/20`

= `1/2`

= 0.5

The probability that the number on the drawn ball is odd is `1/2` or 0.5.