有一个摆地摊的摊主,他拿出3个白球,3个黑球,放在一个袋子里,让人们摸球中奖。只需2元就可以从袋子里摸3个球,如果摸到的3个球都是白球,可得10元回扣,那么中奖的概率是多少?如果一天有300人摸奖,摊主能骗走多少元?( )
A、<img width="20" height="37" src="http://admintk.100xuexi.com/UpLoadImage/2016-08-19/ea88bb3e-a13f-4ef5-9cec-327ac509a0b7.png" />;350
B、<img width="20" height="37" src="http://admintk.100xuexi.com/UpLoadImage/2016-08-19/13194a92-8cd6-4280-b260-93474c166917.png" />;450
C、<img width="20" height="37" src="http://admintk.100xuexi.com/UpLoadImage/2016-08-19/91d3c0e9-5f86-483f-a18b-6493ea823357.png" />;420
D、<img width="19" height="37" src="http://admintk.100xuexi.com/UpLoadImage/2016-08-19/296732cc-cd31-49ae-8f0e-36f316563b73.png" />;450
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