Lesson Transcript

Hi, everybody. My name is Alisha. In this episode, I'm going to talk about how to express fractions and percentages. I'm going to talk about a few different patterns you can use and I'm going to talk about some questions that people have, especially with prepositions. Let's get started.
The first thing that I want to look at is this chart over here. This style of chart, we call a pie chart in English. It looks like a pie. In this case, for this example, I've made it into a data about our favorite desserts, just for example. The black part is people who like ice cream, red is cake, and blue is pie, just for our example. I want to use this to explain how we talk about percentages. Percent is the word that we use for this symbol, this circle slash circle symbol. We use the word percent to explain this. When we want to talk about data in this way, we can use percent before a noun phrase and we use it with the word, "of." To use this data as an example, we would say, for example, "25% of people prefer cake," as in this example. Or here, "50% of people prefer ice cream." When you're using a percentage, please make sure to include the number, of course, followed by percent, 25%, 50%. Follow that, then, with the preposition, "of," 25% of people. In this case, my data is about people's preferences. Your noun phrase may change. In this case, I'm talking about people, people-related data, and their preferences, which is why the end of this sentence includes the words "prefer cake." "People" is my noun. This may change depending on your data and depending on what you need to explain. In general, this is a pattern that you can use to talk about percentages, "25% of," "30% of," to talk about these. Please be careful of this when you are explaining data in this form or maybe in another form as well. Generally, though, if you want to explain your data in running text, meaning just regular text, you can use a pattern like this.
Let's look, though, at something that can cause a little bit of confusion, especially about prepositions. Let's imagine that you need to explain some data in a graph, maybe data that's changing. Here, I have a couple of different patterns. One is red, referring to this red line here and another blue, referring just to this blue line here, just to explain the way that we explain these really. Let's take a look, though. I've made a graph. The data doesn't really matter so much here like what we're actually looking at. I want to focus, though, on the change of the data here. On this axis, I have 10% to 50%, and each dash represents a 10% difference here. The red line, I've made an example pattern which is something increased by 10% here. Please notice I'm using "by" in this sentence. From point 0 on this axis until point 2 here, we see the line increases from 0 to 10%. One way to describe this change is by saying that something, something--in this case, maybe, I don't know, this was about dessert--the number of people who made dessert at home increased by 10%. This "by" shows the degree to which something happened. This is telling us the amount of change. In other words, the degree of change showed by here, "increased by." This is the total change. Let's compare this, then, to the blue line here. The only difference here, I've used the preposition "to," "increased to 20%." This is a sentence that matches this blue line here. I've tried to show from year two to year three. At this point, at year three, in this case, at point 3 on this axis, the data is now at the 20% point. I moved it from 10% at two to 20% at three. Here, I've used, "increased to 20%." This shows us the upper limit of the data. Using 2 shows us the limit of the data, like how far the data went. It's not referring to the amount of change, it's referring to the point at which the data stops or the endpoint for that data. Here, by using "to," we see that this means, actually, the endpoint. "By" refers only to the amount of change. I could say, for example, in this line, the red line, I talked about before, I can say maybe the percentage of people cooking at home increased by 10%, as in my original example. Or, I could also say, in this case, the number of people cooking at home increased to 10%. Both are correct here because both refer to a 10% change, or rather they refer to a 10% change, yes, using "by," but in this case, 10% is also the endpoint for the data for that year. In this case, both "by" and "to" could be correct.
However, with the blue line here, the data here. I'm saying, "it increased to 20% in this time period." That's the endpoint. "To" is showing us the endpoint here. But, if I want to talk about the level, the amount how much this changed, I would need to use the same expression. Here, point 2 was at 10%, point 3 is at 20%. That's a 10% difference here. So, for this blue line, I could say, "in year three, from year two to year three, the number of people cooking increased by 10%." Again, in this case and in this case, the increase is 10% total. Please be careful. "By" shows us the amount of increase, "to" refers to the end point of that increase. In other words, what is the last data point for that time period, for example. Please be careful of your preposition choice in this sentence.
Now, these two sentences show the word increase. You can also use the word decrease, of course, meaning to go down. I've used this as a verb here, but if you want, you can also use increase or decrease as a noun as well. For example, this graph shows an increase. Here, I'm using "increase" as a noun. "Shows an increase of," which we see here. "An increase of 10% from year zero to year two." From year zero to year two, the amount of increase, in other words. How much did it increase, similar to this point here. When I do it this way, "an increase," I need to use "of" before the amount. Please be careful of your preposition choices here. They can make a very big difference, especially "by" and "to." Please be cautious when you're choosing which preposition to use when you're presenting data.
Let's go to the last point for today. The last thing I want to talk about is fraction. These sorts of things you might see in recipes, you might see in data. We call these fractions. Some people have questions. How do you read these? How do you explain them out loud? Let's take a look. I have here three examples. Generally, a general rule, first, is to read the top number here. In this case, I have 1, 2 and 3 as the top numbers. We should read the top number just as you would a regular number: 1, 2, 3, 4, 5, 6, whatever. Read the top number as a regular number in the singular form so 1. You don't need to read it in a plural form. Don't try to change the top number at all. The bottom number, however, we should read the bottom number like you would a date, like a day of the month, like "the third" or "the fourth" or "the fifth," for example. Please use the same sort of numbering as you would for days of the month. In this case, third, sixth, and tenth. We would read them in the same way that we do with dates. We also need to use the plural form for this, unless the top number is a 1. If the top number is a 1, we would read this with a singular form. If the top number is more than 1, we should read this with the plural form. For example, "one-third" would be this one. "Two-sixths." This is a hard one for pronunciation, two-sixths. It's even hard for native speakers to say. "Three-tenths." "One-third," "two-sixths," "three-tenths." If it's difficult for you to say, don't worry, it's hard for me to say too. The plural form should only be used, I'm sorry, the plural form should always be used unless the top number is a 1. Another exception to this rule is if the bottom number here is 2. If, for example, you see something like this, like in a recipe or whatever, 1/2, we don't say "one-second." We don't use that. Here, we just say "half" or "one-half." In a recipe, we would say "half a cup of sugar" or "half a cup of flour," for example. Please keep this in mind. If the number is a 1, use the singular form, if the number is more than 1, use the plural form for the bottom number, and read the bottom number in the way you would read a date.
Those are a few points that I wanted to introduce about percentages, graphs, and fractions, as I've noticed that they can be difficult to explain properly sometimes. I hope that this was useful for you. If you have any questions or if you want to try something out in the comments, please feel free to do so. Thanks very much for watching this episode. I will see you again soon. Bye-bye!

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