<h3>The probability scale</h3><p><strong>Probability</strong> measures how likely an event is, on a scale from <code>0</code> (impossible) to <code>1</code> (certain). An event with probability <code>0.5</code> is as likely to happen as not.</p><h3>Calculating probability</h3><p>For equally likely outcomes, <code>P(event) = (number of favourable outcomes) ÷ (total number of outcomes)</code>. The set of all possible outcomes is the <strong>sample space</strong>. Rolling a fair die, the probability of getting a 4 is <code>1/6</code>, and of getting an even number is <code>3/6 = 1/2</code>.</p><div class="callout"><strong>Kenyan context:</strong> In a Ludo game a player rolls one die. The probability of rolling a six to start is <code>1/6</code>. In a bag of 10 oranges where 3 are unripe, the probability of picking an unripe one at random is <code>3/10</code>. A weather report saying a 70% chance of rain in Kakamega means a probability of <code>0.7</code>.</div>