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Function notation word problem: beach

Learn how to interpret expressions that contain a function within a real-world context. In this video, the function we interpret models the number of people at the beach over time.

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  • male robot hal style avatar for user josh
    Wouldn't it be obvious that there would be more ppl at 5 am than 9 am? It seemed obvious to me.
    (0 votes)
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  • piceratops tree style avatar for user jasmeet.rainal
    Hey guys! This might not be the right place to ask this question but I am having trouble figuring out what to do with a question given to me by my math teacher. The equation is g(x) = 3x^2 + x and it says find x, if g(x) =2, how would I solve this any suggestions?
    (2 votes)
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  • blobby green style avatar for user kimbowers028
    hello can someone help me out with this question :


    What does this mean?

    g(x) has y-values greater than f(x) for x-values between -2 and 2. What will the mathematical notation be for this?

    I don't understand
    (4 votes)
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  • starky seed style avatar for user R Baumann
    In 1980 high school dropouts were 5212 thousand. by 2008 the number dropped to 3118 thousand. what's the linear function that models the decrease?
    (2 votes)
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    • purple pi teal style avatar for user Avishek
      I'm not sure but I'll try. The number of dropouts (say d) is dependent on the year (say y). So d will be a function of y, f(y)=d and since the number d appears to decrease by 74,785 per year since 1980, d for the current year would be less by f(y)=74,785 (y-1980)
      (4 votes)
  • male robot hal style avatar for user Sun
    At , how would choice B be incorrect if 5am is an earlier time than 9am?
    (1 vote)
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    • stelly blue style avatar for user Kim Seidel
      You need to interpret the statement: p(5)<p(9)
      This is not comparing time. This compares the output of the functions, which is numbers of people at the beach at 5am vs at 9am. So, you need to pick an answer that is related to people.

      The expression is saying there are fewer people on the beach at 5am than at 9am. This is item C, but in reverse.
      (2 votes)
  • scuttlebug blue style avatar for user The Travelling Twit
    Kaori is taking a free-throw.

    H(d) models the basketball's height (in meters) at a horizontal distance of d meters from Kaori.

    What does the statement H(R) = 4 mean?

    (Choice A) At a horizontal distance of 4 meters from Kaori, the ball's height was equal to R meters.
    (Choice B) The ball was at the same height at the horizontal distances of 4 meters and R meters.
    (Choice C) At a horizontal distance of R meters from Kaori, the ball's height was equal to 4 meters.

    Where does the variable R come from?
    (1 vote)
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  • starky ultimate style avatar for user Pillager
    this is a bit irrelevant, but at 0.05, the line about the number of people P at the Copacabana beach has always bugged me when i realised it(p ≈ urine)
    does anyone know how to unsee something?
    (1 vote)
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  • piceratops ultimate style avatar for user Aaron
    i can't Understand How a limit's value at a limit is undefinite
    (1 vote)
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  • leaf green style avatar for user G@®®¡sºπWhite
    I don't understand this stuff at all
    (1 vote)
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  • male robot hal style avatar for user Sun
    At choice C, we wouldn't know if there were more people at the beach at 9am than there were at 5am! So wouldn't choice C be incorrect?
    (1 vote)
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Video transcript

Let P of t denote the number of people P at the Copacabana beach in Rio de Janeiro, t hours past midnight on a specific day. What does the statement P of 5 less than P of 9 mean? So before I read these, let's think about this. So this is the number of people five hours past midnight on a specific day. So this is saying that the number of people five hours past midnight is less than the number of people nine hours past midnight at Copacabana beach. So the number of people five hours past midnight is less than the number people nine hours past midnight. Let's get into these choices. The time at which there were five people at the beach is earlier than the time there were nine people. Who know? -- the five and the nine aren't the number of people This is the time. This is the input into the function. The input into the function is time. This gives people as a function of time. You give a time. You give a time. This function P, it outputs P of t, which is equal to the number of people number of people on the beach at time, at time t. So this five -- this is the input. This is the time five hours after I shouldn't say time t. I guess you could say a.m. time -- t hours past midnight at t hours past midnight, hours past past midnight. midnight. So we can definitely rule this out. This isn't talking about five people or nine people. This is talking about five hours after midnight is input and how many people we have five hours after midnight is how many people we have nine hours after midnight. 5 a.m. is an earlier time the 9 a.m. Well, that is a true statement but that's not what this statement is saying. It's not -- this isn't giving us information which is no from, I guess, how we think about time or how we measure time. the 5 a.m. is earlier than 9 a.m. but that's not what this statement is trying to say. So rule that out. There were more people at the beach at 9 a.m. So to be clear, people at the beach at 9 a.m. that's that right over here -- than there were -- than there were at 5 a.m. -- than there were at 5 a.m. Well, that's right over there. And we see -- we see this quantity here is greater than those magenta quantity is indeed greater than this green quantity. The green quantity is less than the magenta quantity, so we would definitely pick that one.