问题 解答题

同时抛掷甲、乙两颗质地均匀的骰子(六个面上分别刻有1,2,3,4,5,6六个数字的正方体).

(Ⅰ)若甲上的数字为十位数,乙上的数字为个位数,问可以组成多少个不同的数,其中个位数字与十位数字均相同的数字的概率是多少?

(Ⅱ)两个玩具的数字之和共有多少种不同结果?其中数字之和为12的有多少种情况?数字之和为6的共有多少种情况?分别计算这两种情况的概率.

答案

(I)由题意知本题是一个等可能事件的概率,

甲有6种不同的结果,乙也有6种不同的结果,故基本事件总数为6×6=36个.

其中十位数字共有6种不同的结果,若十位数字与个位数字相同,十位数字确定后,个位数字也即确定.

故共有6×1=6种不同的结果,即概率为

6
36
=
1
6

(II)两个骰子同时掷的结果可能出现的情况如下表.

数字和
1234567
2345678
3456789
45678910
567891011
6789101112
123456
其中共有36种不同情况,但数字之和却只有2,3,4,5,6,7,8,9,10,11,12共11种不同结果.

从中可以看出,出现12的只有一种情况,概率为

1
36

出现数字之和为6的共有(1,5),(2,4),(3,3),(4,2),(5,1)五种情况,

所以其概率为

5
36

阅读理解

Some say everyday miracles(奇迹) are predestined(注定的)—the right time for the appointed meeting. And it can happen anywhere.

In 2001, 11-year-old Kevin Stephan was a bat boy for his younger brother’s Little League team in Lancaster, New York. It was an early evening in late July. Kevin was standing on the grass away from the plate, where another youngster was warming up for the next game. Swinging his bat back and forth, giving it all the power an elementary school kid could give. The boy brought the bat back hard and hit Kevin in the chest. His heart stopped.

When Kevin fell to the ground, the mother of one of the players rushed out of the stands to his aid. Penny Brown hadn’t planned to be there that day, but at the last minute, her shift(换班)at the hospital had been changed to see her son’s performance. She was given the night off. Penny bent over the senseless boy, his face already starting to turn blue, and giving him CPR(心肺复苏术), breathing into his mouth and giving him chest compressions. And he revived in the end.

After his recovery, he became a volunteer junior firefighter, learning some of the emergency first-aid techniques that had saved his life. He studied hard in school and was saving money for college by working as a dishwasher in a local restaurant in his spare time.

Kevin, now 18, was working in the kitchen when he heard people screaming, customers in confusion, employees rushing toward a table. He hurried into the main room and saw a woman there, her face turning blue, her hands at her throat. She was choking.

Quickly Kevin stepped behind her, wrapped his arms around her and clasped his hands. Then, he used skills he’d first learned in Scouts. The food that was trapped in the woman’s throat was freed. The colour began to return to her face.

“The food was stuck in my throat. I couldn’t breathe,” she said. She thought she was dying. “I was very frightened.”

Who was the woman?

Penny Brown.

小题1: The author wrote the passage to show us that         .

A.miracles are predestined and they can happen anywhere

B.whoever helps you in trouble will get a reward one day

C.God will help those who give others a helping hand

D.miracles won’t come without any difficulty sometimes小题2:Which of the following statements is TRUE of Kevin Stephan?

A.He was hit in the face by a boy and almost lost his life.

B.He was a volunteer junior firefighter, teaching the players first-aid skills.

C.He worked part-time in a local restaurant to save money for college.

D.He saved Penny Brown though he didn’t really know how to deal with food choke.小题3:Why did Penny Brown change her shift and was given the night off that night?

A.She was invited to give the players directions.

B.She volunteered to give medical services.

C.She was a little worried about his son’s safety.

D.She came to watch her son’s game and cheered for him.小题4:The underlined word “revived” in the third paragraph most likely means       .

A.came back to life

B.became worse

C.failed

D.moved小题5: When Kevin knew the woman was Penny Brown, probably he first felt       .

A.happy

B.surprised

C.sad

D.worried

问答题 简答题