 字幕列表 影片播放

• Brandon ate 5 slices of apple-- of pie.

• I'm just assuming it's apple pie.

• They didn't tell me that.

• Gabriela ate 3 slices.

• If there were originally 9 slices,

• what fraction of the pie was eaten?

• So let me see if I can draw this thing out.

• So let me draw the pie.

• I will draw the pie in a yellowish color.

• So let me try my best.

• So let's see how good I am at drawing a pie.

• So I'll just draw it from the top view as a circle.

• And there're 9 slices.

• I think it's a reasonable assumption

• to say that they're 9 equal slices.

• So we have 9 equal slices of pie.

• And I'll just make sure they're initially 9 equal slices.

• What fraction of the pie was eaten?

• So let's first divide this into 9 sections.

• So one way I could do that, I could divide it into 3 sections

• first, so it looks like a peace symbol.

• It actually looks more like the Mercedes emblem.

• So I'll draw it into 3 sections first.

• Then I'll do each of those into 3 sections, and I'll have 9.

• So let's see, I'll draw like that and like that.

• Keep in mind, I'm trying to make these as equal as possible.

• So bear with me if they don't look 100% equal,

• but I'm trying.

• I am trying my best.

• So 9 equal slices-- so that looks pretty respectable.

• So here's our pie that initially had 9 equal slices.

• Now, they tell us that Brandon ate 5 slices of pie.

• So Brandon eats-- he seems like a hungry young man--

• so he eats 1, 2, 3, 4, 5.

• You could say that he ate 5/9 of the pie.

• But that's not it.

• That's not what they're asking.

• It's saying total, not just how much did Brandon eat,

• but how much was eaten total between Brandon and Gabriela.

• And they tell us Gabriela ate 3 slices.

• So she ate 1-- sounds like they didn't really

• eat dinner-- 1, 2, 3.

• So now let's answer their question.

• What fraction of the pie was eaten?

• Well, we know that there was a total of 9 equal slices of pie.

• What fraction was eaten?

• Well, as we see, 1, 2, 3, 4, 5, 6, 7, 8.

• 8/9 of the pie was eaten.

• So let's actually type that in.

• And then we will do it right over here.

• We'd say 8, and we use that little slash symbol

• on your computer like this.

• 8 over 9 or 8 divided by 9 or 8/9 of the pie was eaten.

• Let's do a couple more of these.

• Ishaan ate 2 slices of pizza.

• Omar ate 3 slices.

• If there were originally 8 slices,

• what fraction of the pie is remaining?

• So this is interesting.

• Actually, let me copy and paste this

• so that I can do it on my little notepad right over here.

• So let's do it right over-- trying to find some space.

• There you go.

• Let me put that in here.

• So the same thing, we have-- well,

• this is a pizza now, not a pie.

• And so pizza I will draw in brown.

• It has 8, and we can assume it's initially 8 equal slices.

• So it's actually a little bit easier to draw 8 equal slices,

• since 8 is an even number.

• So let's see.

• That is my best attempt at drawing a circle.

• And let's see, first I can divide the pizza into 2 slices,

• then I can divide it into 4 slices.

• And I'm going to try to make them look as equal as possible.

• And now I'm going to-- with two more cuts,

• I should be able to get 8 so-- and one more just like this.

• So there you have it, a pizza that has 8 equal slices.

• Now, they tell us Ishaan ate 2 slices of pizza.

• So he eats 1, 2 slices of pizza.

• Omar ate 3 slices.

• Omar ate 3.

• So he eats 1, 2, 1, 2, 3 slices of pizza.

• Now, you might immediately say, oh, OK,

• the answer to this must be 1, 2, 3, 4, 5.

• It must be that they ate 5 slices of pizza

• over a total of 8 slices of pizza.

• So they ate 5/8 of the pizza.

• You would be right in saying that they ate 5/8 of the pizza,

• because they ate 1, 2, 3, 4, 5 out of a total of 8 pieces.

• But that's not what this question is asking.

• They are asking, what fraction of the pizza is remaining?

• So what's left over after Ishaan and Omar

• had their go at the pizza?

• Well, what's remaining is 1, 2, 3 slices.

• So what's remaining is 3 out of the original 8 equal parts

• or 3/8 of the pizza is remaining.

• So let's input that.

• So we could go right here.

• And we would say 3 over 8, 3/8, is remaining.

• So let's check our answer, and we got it right.

Brandon ate 5 slices of apple-- of pie.

A2 初級

計算出還剩多少比薩餅｜分數｜四年級｜可汗學院 (Figuring out how much pizza is left | Fractions | 4th grade | Khan Academy)

• 66 5
VoiceTube 發佈於 2021 年 01 月 14 日