问题 解答题
甲、乙两队在进行一场五局三胜制的排球比赛中,规定先赢三局的队获胜,并且比赛就此结束,现已知甲、乙两队每比赛一局,甲队获胜的概率为
3
5
,乙队获胜的概率为
2
5
,且每局比赛的胜负是相互独立的,问:
(1)甲队以3:2获胜的概率是多少?
(2)乙队获胜的概率是多少?
答案

(1)甲队以3:2获胜,说明前4场比赛甲队赢了2场,且甲队赢了第五场,

设甲队以3:2获胜的概率为P1,则P1=

C24
(
3
5
)
2
(
2
5
)
2
3
5
=
648
3125

(2)乙队获胜的情况有2种:乙队连赢3局;或者乙队以3:2获胜.

设乙队获胜的概率P2,则P2=(

2
5
)3+
C24
(
3
5
)
2
(
2
5
)
2
2
5
=
992
3125

阅读理解

We are just getting older and older with each New Year. Vigor and wisdom

are draining, and bit by bit we are moving away from the amazement of youth.

Yet neither fear nor anxiety helps retain youth. Instead, a few living habits

help maintain.

●Laugh to your heart's content as much as you can. Laughter helps reduce

pressure and improve your immune system, which makes people look 8 years younger.

●Keep an eye on your blood pressure. Those with a blood pressure of 115/75mmHg look 2.5 years younger than those above 160/90mmHg.

●Quit smoking and avoid passive smoking. This can take 8 years off your appearance.

●Spare some time for exercises each day. Exercises need not be tiring. A 20 minute walk every day makes people look 5 years younger.

●Keep learning and absorb something new each day. Speak the same language as the young people. Learning something every day makes people look 2.5 years younger.

●Keep other pressures under control. Too much pressure makes people look 30 years older. If they are good at networking and manage to keep pressure under control, they will look 30 years younger.

●Secure high quality medical care insurance and do whole body check regularly. For those contracted with chronicle diseases, proper treatment and qualification of the diseases makes people look 12 years younger than what they would without proper treatment.

63. The passage is mainly about _________.

A. the important of retaining youth    B. some tips helping people retain youth

C. moving away from the amazement of youth

D. the connections between the health and the age

64. The underlined sentence “This can take 8 years off your appearance.” means _________.

A. Smoking and passive smoking can make you look 8 years younger

B. Smoking and passive smoking can make you die 8 years ahead

C. Giving up smoking and avoiding passive smoking can make you live 8 years longer

D. Giving up smoking and avoiding passive smoking can make you look 8 years younger

65. According to the passage, we can know that _________.

A. exercises properly every day helps people retain youth

B. if you want to be 30 years younger you must keep other pressures under control

C. doing whole body check regularly can make people look younger

D. fear and anxiety are a part of our life, which help people realize the importance of keeping youth

判断题