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Current time:0:00Total duration:2:36

Function notation word problem: beach

CCSS.Math:

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 let's before I even read this let's think about this so this is the number of people 5 hours past midnight on a specific day so this is saying that the number of people 5 hours past midnight is less than the number of people 9 hours past midnight at Copacabana beach so the number of people 5 hours past midnight is less than the number of people 9 hours past midnight let's look at these choices the time at which there were 5 people at the beach is earlier than the time there were 9 people well no the five and the nine aren't the number of people this is the time this was 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 5 this is the input this is the time 5 hours after or I not in session C at time T so 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 and nine people this is talking what 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 5:00 a.m. is an earlier time than 9:00 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 we just know from I guess how we think about time how we measure time that 5:00 a.m. is rather than item but that's not what this statement is trying to say so we'll rule that out there were more people at the beach at 9:00 a.m. so to be clear people at the beach I am that's that right over here then there were then there were at 5:00 a.m. then there were at 5:00 a.m. well that's right over there and we see where we see that this quantity here is greater than those magenta quantity is indeed greater than this green quantity or the green quantity is less than the magenta quantity so we would definitely pick that one