1.用树状图表示如图56所示.
(1)由树状图可知P(三辆车全部继续直行)=1/27.
(2)由树状图可知P(两辆车向右转,一辆车向左转)=3/27=1/9.
(3)由树状图可知P(至少有两辆车向左转 )=7/27.
1.解:(1)从左到右依次填0.56,0.60,0.52,0.52,0.49,0.51,0.50.
(2)P (投中)≈0.5
2.提示:1/6≈0.17.
解:从上到下依次填0.940,0.935,0.940,0.845,0.870,0.883,0.891,0.898,0.904,0.901,∴种子发芽的概率大约为0.9,,1000kg种子中大约有1000×(1-0.9)=100kg不能发芽.