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. 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". You can use "%" to express percent. So 35% means 35 out of 100, and 15% means 15 out of 100. 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.
You can also express probability by using ratios. 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. |
