Prática de Shadowing: Math Antics - Percents Missing Total - Aprenda a falar inglês com vídeo
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Hi! Welcome to Math Antics. In our last lesson about percents, we learned that there’re three main types of percent problems because there’s three different numbers that could be missing.
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Those three numbers are the ‘part’, the ‘total’, and the ‘percent’.
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They’re just the three variable in the percentage equation.
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The forth number is always 100, since that’s what percent means: per 100.
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In the last two videos, we learned how to solve problems where the ‘part’ was unknown and where the ‘percent’ was unknown.
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In this video, we’re gonna learn how to solve problems where the ‘total’ is unknown or missing.
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With this type of problem, you’ll be told what the percent is, and you’ll be told what part of the total you have.
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But you’ll need to figure out what that total itself is.
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Here’s an example of a problem like that: Your friend has a bag of marbles, and he tells you that 20% of the marbles are red.
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If there’s 7 red marbles, how many marbles does he have altogether?
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Okay, so how do you know that it’s the total that’s missing in this problem?
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Well, the word “altogether” is a big clue because it means almost the same thing as “total”.
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So, if the question has words like, “altogether”, or “in all”, or “total”, or “whole”, or “entire” those can help you know that you need to find the total.
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And another way that we can tell is by the numbers that we ARE given.
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In this problem, we know that the percent is 20, and we’re also told that PART of the marbles are red, so we know that the PART is 7.
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So that means that it must be the total that’s missing!
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Alright then, so how do we figure out what the total is?
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Well, using a little algebra we can re-arrange our percent equation like this: What this new form of the equation tells us is that, if we take the ‘part’ and multiply it by 100, and then we divide that by the ‘percent’, we’ll get the ‘total’.
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That seems simple enough. It’s just two steps!
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Let’s try it out on our word problem about the marbles.
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We know that the ‘part’ is 7, so step one is to just multiply that part by 100.
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7 × 100 is 700.
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And in step two, we take that 700 and divide it by the ‘percent’, which we’re told is 20.
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Okay, 700 divided by 20…. hmmm….
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Well, we could use a calculator to divide, but this doesn’t seem too hard, so I’ll just do the division the long way.
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20 is to big to divide into the first digit so we’ll need to include the digit next to it as well.
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Now we ask, “How many ’20’s does it take to make 70 or almost 70”.
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That would be 3 because 3 × 20 is 60.
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70 minus 60 leaves 10 as the remainder.
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And then we bring down the zero and then we ask, “How many ’20’s will divide into 100?” Ah-ha… 5, because 5 × 20 is 100, so that leaves no remainder.
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So 700 divided by 20 is 35.
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And that means that the total number of marbles is 35.
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And in a problem like this, you can always check your answer by making sure that the fraction of the ‘part’ over the ‘total’ would give you the correct percent.
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For example, in this case, you could make sure that the fraction 7 over 35 would really be 20%.
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Now that wasn’t so tough, was it?
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Let’s see one more example to make sure you’ve got the procedure down before you try some on your own.
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The next problem says: A high school marching band has 12 flute players.
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If 8% of the band members play the flute, then how many members are in the entire band?
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Okay, so the smaller ‘part’ in this problem is 12 since there’s 12 flute players.
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And we’re told that they make up 8 percent of the band, so the ‘percent’ is 8.
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Again, it’s the ‘total’ that’s missing, and to find it, we just need to follow our 2-step procedure.
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For step one, we multiply the ‘part’ by 100: 12 × 100 = 1,200 For step two, we divide that 1,200 by the percent, which is 8.
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1,200 divided by 8 equals 150.
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Great… that means that the total number of band members is 150.
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And again, you can always check your answer the way we did in the last example.
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Alright… that does it for this lesson.
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Remember… the key to getting really good at math is to do it yourself.
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Doing practice problems on your own will help you become a great problem solver.
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Good luck! Thanks for watching Math Antics and I’ll see ya next time.
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Learn more at www.mathantics.com
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Por que praticar a conversação com este vídeo?
Este vídeo de Math Antics proporciona uma excelente oportunidade para praticar a prática de conversação em inglês. Ao assistir, você não apenas aprende a resolver problemas de porcentagens, mas também desenvolve suas habilidades de fala ao repetir as explicações. Isso é conhecido como shadow speech, que envolve imitar o que você ouve, aprimorando sua pronúncia e fluência. Aproveitar vídeos educativos como este torna o aprendizado de inglês mais dinâmico e interessante, permitindo aplicar o vocabulário novo em contextos práticos e cotidianos.
Gramática & Expressões em Contexto
No vídeo, o apresentador utiliza várias estruturas gramaticais úteis que podem ser aplicadas em diferentes contextos. Aqui estão algumas delas:
- "How do you know that...?" - Uma maneira de questionar e verificar a compreensão. Você pode usar estruturas semelhantes para expressar dúvidas.
- "What this new form of the equation tells us..." - Este fraseado serve para apresentar explicações detalhadas. Aprender a estruturar suas respostas dessa forma pode ser muito útil.
- "So that means that..." - Essa expressão é excelente para concluir uma ideia ou uma explicação. Ela facilita a ligação entre as partes do discurso.
Usar essas construções em conversações ajuda a organizar suas ideias e a se comunicar de maneira mais eficiente. Experimente criar frases semelhantes com o vocabulário que você aprendeu!
Traps Comuns de Pronúncia
Durante o vídeo, alguns termos podem ser desafiadores para a pronúncia, especialmente para falantes não nativos. Abaixo, destacamos algumas armadilhas comuns:
- "percent" - A pronúncia correta pode ser difícil, especialmente com o final "cent". Pratique a palavra lentamente antes de aumentá-la gradualmente.
- "total" - Este é um termo fundamental e é importante garantir que a ênfase esteja na primeira sílaba.
- "altogether" - A velocidade ao pronunciar pode alterar a clareza. Tente segmentar as sílabas de forma clara ao falar.
Praticar essas palavras através da prática de conversação em inglês e do shadow speak pode ajudar a consolidar a pronúncia correta, tornando suas interações em inglês mais naturais. Use o conteúdo dos vídeos, como este, para melhorar sua fluência e compreensão!
O que é a Técnica de Shadowing?
Shadowing é uma técnica de aprendizado de idiomas com base científica, originalmente desenvolvida para o treinamento de intérpretes profissionais. O método é simples, mas poderoso: você ouve áudio em inglês nativo e repete imediatamente em voz alta — como uma sombra seguindo o falante com 1-2 segundos de atraso. Pesquisas mostram melhora significativa na precisão da pronúncia, entonação, ritmo, sons conectados, compreensão auditiva e fluência na fala.