There are only 3 red balls in a pocket, and a ball is randomly drawn from the pocket. To make the probability of drawing a red ball be (1/2), how many balls of other colors must be put into the pocket.
一个口袋里只有3个红球，从口袋里任意摸出一个球，要使摸出的红球的可能性为(1/2)，还要往口袋了放多少个其它颜色的球．
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">3 / (1/2)</gadget>
<output>6</output>

<gadget id="calculator">6 - 3</gadget>
<output>3</output>

<result>3</result>