问题 解答题

某大学举办“我爱记歌词”校园歌手大赛,经过层层选拔,有5人进入决赛,决赛办法如下:选手参加“千首电脑选歌”演唱测试,测试过关者即被授予“校园歌手”称号,否则参加“百首电脑选歌”演唱测试。若“百首电脑选歌”测试过关也被授予“校园歌手”称号,否则被彻底淘汰。若进入决赛的5人“千首电脑选歌”演唱测试过关的概率是0.5,“百首电脑选歌”演唱测试合格的概率是0.8,而且每个人每轮测试是否合格是相互独立的,试计算(结果精确到0.01)

(1)恰好有两人参加“百首电脑选歌”演唱的概率;

(2)平均有几人参加“百首电脑选歌”演唱(保留小数);

(3)至少一人被最终淘汰的概率。

答案

(1)每人参加“百首电脑选歌” 演唱的概率是1-0.5,且每人是否参加相互独立,所以恰好有两人参加“百首电脑选歌”演唱的概率是

="0.31                          "

(2)由条件知,参加“百首电脑选歌”演唱的人数X服从二项分布B(5,0.5),

即X的期望是EX="5*0.5=2.5,"

平均有2.5人参加“百首电脑选歌”演唱                        

(3)某人被最终淘汰的概率是(1-0.5)(1-0.8)=0.1,不被淘汰的概率就是0.9

由题意,每人是否被淘汰是相互独立的,

所以至少一人被最终淘汰的概率是

阅读理解

As a parent you might never guess all the ways a good imagination benefits your child. It helps a preschooler(学龄前儿童):

Develop social skills

As children play pretend, they explore relationships between family members, friends and co­workers and learn more about how people interact. Playing doctor, they imagine how physicians care for their patients. Playing house, they learn more about how parents feel about their children. Imaginative play helps develop empathy(同情) for others. If children can imagine how it feels to be left out of a game or to lose a pet, they are better able to help those in need. They become more willing to play fair, to share, and to cooperate.

Build self­confidence

Young children have very little control over their lives. Imagining oneself as a builder of skyscrapers(摩天大楼) or a superhero defending the planet is empowering to a child. It helps them develop confidence in their abilities and their potential.

Boost intellectual growth

Using the imagination is the beginning of abstract thought.Children who can see a king's castle in a mound(堆) of sand or a delicious dinner in a mud pie are learning to think symbolically(象征性地). This skill is important in school where a child will have to learn that numerals symbolize groups of objects, letters symbolize sounds, and so on.

Practice language skills

Kids who play pretend with their friends do a lot of talking.This helps boost their vocabulary, improve sentence structure and promote communication skills.

Work out fears

Playing pretend can help children work out their fears and worries. When children role­play about the big, bad monster under the bed, they gain a sense of control over him and he doesn't seem quite so big or so bad. Imaginative play also helps kids vent(发泄) confusing feelings they might have, such as anger toward a parent or compete with a new sibling(兄弟姐妹).

To encourage your youngster's imagination, read to him every day. Books offer children the opportunity to visit other worlds and create new ones of their own.

For generations children have enjoyed reading the story of Peter Pan because Peter takes them on fascinating adventures.Reader's Digest Young Families offers a beautiful typical Disney edition of Peter Pan, which is an iParenting Media Award winner. Click here to find out how you can get this classic story along with 2 free books-Bambi and Pinocchio.

小题1:What's NOT the advantage of children having a good imagination?

A.Understanding the other people's feelings and problems.

B.Expressing their feelings like anger.

C.Having a strong faith in their own abilities and potential.

D.Helping them form a good habit of reading stories.小题2:What does the underlined word “Boost” mean?

A.Improve.

B.Limit.

C.Push.

D.Praise.小题3:From the last paragraph we can learn that ________.

A.Reader's Digest Young Families wins an iParenting Media Award

B.Disney edition of Peter Pan can be got online for free

C.the story of Peter Pan has been popular with kids

D.Bambi and Pinocchio are offered for free because of bad sales小题4:What's the purpose of writing the article?

A.To tell readers the benefits of encouraging children's imagination.

B.To introduce some wonderful Disney stories to readers.

C.To provide ways of helping make kids more imaginative.

D.To persuade parents to buy the Disney edition of Peter Pan.

判断题