There are 6 balls in a pocket that are exactly the same except for the color, so that the probability of drawing a red ball is (1/2), how many red balls should be placed in the pocket.
在一个口袋里放着除颜色外都一模一样的6个球，使得摸出红球的可能性是(1/2)，口袋里要放多少个红球．
<result>3</result>