There are 4 red and 1 white balls in a cloth bag, all of which are the same except for the color, what is the probability of drawing a red ball?
布袋里有4红、1白色球，除颜色外其它都相同，摸出红球的可能性是多少．
<gadget id="calculator">4 + 1</gadget>
<output>5</output>

<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<result>4/5 = around 0.8</result>