Question

【题目】

A ratio compares two numbers. For example, if you have 3 pens and 4 pencils, the ratio of pens to pencils is 3 to 4. 【1】 3 to 4, 3:4 and 3/4. One type of ratio is expressing (表示) numbers as a percent. A percent is the ratio of a number to 100. In other words, a percent compares one number to 100. The percent means "per hundred". 【2】 You can use "%" to express percent. So 35% means 35 out of 100, and 15% means 15 out of 100. 【3】 Probability means the chance (可能) of some things happening in the future. For example, if there is a 90% chance of rain, 90 times out of 100, it will rain. That is a very high probability. However, if the weatherman says that there is only a 10% chance of rain, then 10 times out of 100, it will rain. 【4】

You can also express probability by using ratios. 【5】 5 of them are black while only 1 of them is red. If you choose a pen at random (随机地) from the pencil box, then the probability of choosing a black Den are 5 to 6, or 5/6. On the other hand, the probability of choosing a red pen is only 1 to 6, or 1/6.

A. So, 60 percent of something means 60 out of 100.

B. For example, perhaps you have 6 pens that all look alike in your pencil box.

C. The ratio can be written in three ways.

D. That is a very low probability.

E. Percents are helpful when expressing the probability.

Answer 1

【答案】

【1】C

【2】A

【3】E

【4】D

【5】B

【解析】

本文介绍了比率可以用百分数来表示，百分数在表示概率方面很有帮助，可以用比率表示可能性。

【1】根据“3 to 4 , 3:4 and 3/4.”可知，此处指的是比率可以用三种方式来表达，故选C。

【2】根据“So 35% means 35 out of 100, and 15% means 15 out of 100.”可知，百分之三十五表示35/100，因此百分之六十表示60/100，故选A。

【3】根据“Probability means the chance (可能) of some things happening in the future.”可知，百分数在表示概率方面很有帮助，故选E。

【4】根据“However if the weatherman says that there is only a 10% chance of rain, then 10 times out of 100, it will rain.”可知，然而，如果天气预报员说下雨的可能性只有10%，那么100次中有10次会下雨。因此，那是很低的可能性，故选D。

【5】根据“5 of them are black while only 1 of them is red.”可知，5支是黑色的，1支是红色的，故此处指的是6支钢笔，故选B。