问题 选择题

为了估计湖里有多少条鱼,先从湖里捕捞100条鱼都做上标记,然后放回湖中去,经过一段时间,待有标记的鱼完全混合于鱼群后,第二次再捕捞100条鱼,发现其中10条有标记,那么你估计湖里大约有鱼           (    )

A.500条

B.600条

C.800 条

D.1000条

答案

答案:D

分析:在样本中“捕捞100条鱼,发现其中10条有标记”,即可求得有标记的所占比例,而这一比例也适用于整体,据此即可解答.

解答:解:设湖中有x条鱼,则100:10=x:100,解得x=1 000(条).

故选D.

阅读理解

    Do you scream on a roller coaster ride? You slowly climb up a steep slope until an almost vertical(垂直的) drop, and then... Ahhhhhhhh! Thrill-seekers like me are in luck because theme parks are pushing the boundaries of technology to create the fastest, tallest, scariest roller coasters the world has ever known.

Alton Towers in Britain opened the world's first 14-1oop roller coaster a few months ago, called The Smiler. Over in Abu Dhabi, Ferrari World claims to have the world's fastest one. Ferrari World's Formula Rossa ride sends out passengers from 0-240km/h in just 4. 9 seconds. During this rapid acceleration they experience G-forces only fighter pilots usually  feel: Up to 4. 8G. The designer of several rides at Alton Towers, said: "While we can stand 6-8Gs for very short periods of  time, ff we experience 5G for more than five seconds we're likely to "black out."

On modern roller coasters passengers experience about 3G in tight turns and loops. But while we may have reached the limit in terms of G-forces, there is no technological limit to how fast or how high roller coasters can go---it's all down to money. Alton Towers' The Smiler cost ~18m to build.

Some companies are finding other ways to keep us amused. There's a move towards indoor rides where the experience is improved by audio-visual technologies. For example, a company called Dynamic Structures is currently developing a "coal-mine-themed" ride for a client in Dubai that will combine speed and G-forces with 3D projection effects and robotics, which will trick your brain into thinking you're really falling.

I can't wait to enjoy this one. What about you: Do you like being upside down?

小题1:The underlined phrase "black out" in the second paragraph probably means  ....  .

A.stop breathing

B.lose consciousness for a short time

C.lose memory forever

D.bleed to death小题2: We can learn from the passage that __

A.all the theme parks are creating the fast roller coasters

B.the Smiler sends out passengers from 0-240km/h in just 4.9 seconds

C.it is unusual for fighter pilots to feel up to 4.8G

D.the more the money is spent, the faster the roller coaster can go小题3: The feature of the "coal-mine-themed" ride is

A.3Dtechnologies

B.indoor rides

C.G-forces

D.dynamic structures小题4: What is the best title for the passage?

A.The Fastest Roller Coaster

B.The Smiler and G-forces

C.Screaming for Fun

D.The New Technology

单项选择题 A2型题