It is as likely to draw a red ball from a pocket with 2 red balls and 1 yellow ball as from a pocket with 4 red balls and 2 yellow balls.
从有2个红球、1个黄球的口袋中摸同红球与从有4个红球、2个黄球的口袋中摸出红球的可能性是一样大的．
<result>2</result>