将一枚质地均匀的骰子连掷两次，记向上的点数分别为a，b．（Ⅰ）求事件“a+b=8”的概率；（Ⅱ）求事件“
\u7528\u5b9e\u9a8c\u7684\u65b9\u6cd5\u4f30\u8ba1\u4e0b\u5217\u4e8b\u4ef6\u53d1\u751f\u7684\u6982\u7387\uff1a\u968f\u673a\u63b7\u4e00\u679a\u5747\u5300\u7684\u9ab0\u5b50\uff0c\u6bcf\u6b21\u8bd5\u9a8c\u63b7\u4e24\u6b21\uff0c\u4e24\u6b21\u9ab0\u5b50\u7684\u70b9\u6570\u548c\u4e3a6.\u63b7\u51fa1+5 p=1/36
\u63b7\u51fa5+1 p=1/36
\u63b7\u51fa4+2 p=1/36
\u63b7\u51fa2+4 p=1/36
\u63b7\u51fa3+3 p=1/36
p=5/36
\u540c\u65f6\u63b7\u4e24\u4e2a\u8d28\u5730\u5747\u5300\u7684\u9ab0\u5b50\u5171\u670936\u79cd\u60c5\u51b5 1 2 3 4 5 6 1 \uff081\uff0c1\uff09 \uff081\uff0c2\uff09 \uff081\uff0c3\uff09 \uff081\uff0c4\uff09 \uff081\uff0c5\uff09 \uff081\uff0c6\uff09 2 \uff082\uff0c1\uff09 \uff082\uff0c2\uff09 \uff082\uff0c3\uff09 \uff082\uff0c4\uff09 \uff082\uff0c5\uff09 \uff082\uff0c6\uff09 3 \uff083\uff0c1\uff09 \uff083\uff0c2\uff09 \uff083\uff0c3\uff09 \uff083\uff0c4\uff09 \uff083\uff0c5\uff09 \uff083\uff0c6\uff09 4 \uff084\uff0c1\uff09 \uff084\uff0c2\uff09 \uff084\uff0c3\uff09 \uff084\uff0c4\uff09 \uff084\uff0c5\uff09 \uff084\uff0c6\uff09 5 \uff085\uff0c1\uff09 \uff085\uff0c2\uff09 \uff085\uff0c3\uff09 \uff085\uff0c4\uff09 \uff085\uff0c5\uff09 \uff085\uff0c6\uff09 6 \uff086\uff0c1\uff09 \uff086\uff0c2\uff09 \uff086\uff0c3\uff09 \uff086\uff0c4\uff09 \uff086\uff0c5\uff09 \uff086\uff0c6\uff09\uff0e\uff081\uff09\u6ee1\u8db3\u4e24\u4e2a\u9ab0\u5b50\u70b9\u6570\u76f8\u540c\uff08\u8bb0\u4e3a\u4e8b\u4ef6A\uff09\u7684\u7ed3\u679c\u67096\u4e2a\u5373\uff1a\uff081\uff0c1\uff09\uff0c\uff082\uff0c2\uff09\uff0c\uff083\uff0c3\uff09\uff0c\uff084\uff0c4\uff09\uff0c\uff085\uff0c5\uff09\uff0c\uff086\uff0c6\uff09\uff0c\u6240\u4ee5 P(A)\uff1d636\uff1d16\uff1b\uff084\u5206\uff09\uff082\uff09\u5c06\u4e24\u4e2a\u9ab0\u5b50\u7684\u70b9\u6570\u7684\u548c\u4e3a8\u8bb0\u4e3a\u4e8b\u4ef6B\uff0c\u5219\u6ee1\u8db3\u8be5\u4e8b\u4ef6\u6761\u4ef6\u7684\u7ed3\u679c\u6709\uff086\uff0c2\uff09\uff0c\uff085\uff0c3\uff09\uff0c\uff084\uff0c4\uff09\uff0c\uff083\uff0c5\uff09\uff0c\uff082\uff0c6\uff09\u51715\u4e2a\uff0c\u6240\u4ee5P\uff08B\uff09=536\uff0e\uff083\uff09\u5c06\u81f3\u5c11\u6709\u4e00\u4e2a\u9ab0\u5b50\u70b9\u6570\u4e3a3\u8bb0\u4e3a\u4e8b\u4ef6C\uff0c\u5219\u6ee1\u8db3\u8be5\u4e8b\u4ef6\u6761\u4ef6\u7684\u7ed3\u679c\u5171\u670911\u4e2a\uff0c\u6240\u4ee5 P\uff08C\uff09=1136\uff0e\uff088\u5206\uff09
| （Ⅰ）由题意得，掷骰子1次，其向上的点数有6种情况， 则将一枚骰子连掷两次，基本事件的总个数是6×6=36，即（a，b）的情况有36种， 事件“a+b=8”包含基本事件：（2，6），（3，5），（4，4），（5，3），（6，2），共5个， ∴所求事件的概率为
（Ⅱ）若方程ax 2 +bx+1=0有实根，则必有△=b 2 -4a≥0， 若a=1，则b=2，3，4，5，6， 若a=2，则b=3，4，5，6， 若a=3，则b=4，5，6， 若a=4，则b=4，5，6， 若a=5，则b=5，6， 若a=6，则b=5，6， ∴事件“方程ax 2 +bx+1=0有实根”包含基本事件共5+4+3+3+2+2=19个， ∴所求事件的概率为
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