There are 5 red balls and 8 white balls in a box, all of which are identical except for their color. If a ball is drawn at random from the box, what is the probability of drawing a red ball?
箱子里有5个红球和8个白球，球除颜色外完全相同，从中任意摸出一个球，摸出红球的可能性是多少
<gadget id="calculator">5 + 8</gadget>
<output>13</output>

<gadget id="calculator">5 / 13</gadget>
<output>5/13 = around 0.384615</output>

<result>5/13 = around 0.384615</result>