问题 解答题

小伟和小欣玩一种抽卡片游戏:将背面完全相同,正面分别写有1,2,3,4的四张卡片混合后,小伟先从中随机抽取一张.记下数字后放回,混合后小欣再随机抽取一张,记下数字.如果所记的两数字之和大于4,则小伟胜;如果所记的两数字之和不大于4,则小欣胜.

(1)若小伟先抽取的卡片数字是1,问这时两人谁获胜的可能性大?为什么?

(2)请用列表或画树形图的方法,分别求出这种游戏中小伟,小欣获胜的概率.

答案

解:(1)由(1)的图表,可得共4种情况,

其中小伟胜的1种,有小欣胜的有3种;

故P(小伟胜)=,P(小欣胜)=,所以小欣获胜的概率大.

(2)如图:

故可能出现的结果有16个,其中数字和大于4的有10个,

数字和不大于4的有6个.

故P(小伟胜)==;P(小欣胜)==

多项选择题
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During my high school years, the most important thing was what I was wearing to the Friday night dance and who I was taking.Although college was talked about, it was the least of my worries.

When I was graduating eighth grade and starting high school, my elder brother was graduating twelfth grade and going onto college.For my graduation, he gave me a card in which he wrote, “Enjoy your four years…they go by fast.” I remember not believing him then, but looking back…he was right.Those four years shaped who I was as a person, pushed me to my limit and encouraged me to become an adult.

However, I was so completely absorbed in my junior and senior years of high school, that when someone spoke of college I brushed it off.I wasn't ready to leave my comfort zone of having all of my closest friends together and knowing what every single day was going to be like.Studying was something I did only AFTER I nailed my half-time dance performance.I knew my parents wanted me to go to college, so I told them I would go to community college (社区学院) and I didn’t worry about my SAT(美国大学入学考试)scores.

When my senior year passed and everyone graduated and went off to their own college, I started to wish I had done the same.My friends were living away, meeting new people, discovering new places, and I was living at home and driving to and from class every day.It seemed exactly like high school.I hated it! I thought college was supposed to be different! Why didn’t I take more time to research colleges and do the same? I ended up loving college and wishing I had four years to enjoy the campus atmosphere instead of two.

My advice to anyone thinking about attending college is to think about it very seriously and look into all of your choices well ahead of time.Now I have graduate and I am working full time and I would do anything to go back to my high school days for a second chance!

小题1:Why didn’t the author worry about his SAT scores?

A.He wanted to go to community college.

B.He had been admitted for his gift in dance.

C.He was well prepared for the exam.

D.He believed his brother would help him.小题2:When in high school, the author          

A.drove to and from class every day.

B.buried himself in his study all the time.

C.enjoyed talking about future college life.

D.lived in the school except on holidays.小题3:What did the author’s brother mean by “Enjoy your four years…they go by fast”?

A.He wished the author to have more dance.

B.He advised the author to value the years.

C.He encouraged the author to leave his comfort zone.

D.He suggested the author aim at a community college.小题4:Talking of his high school years, the author feels     

A.regretful

B.lonely

C.angry

D.pleased