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### Course: Algebra (all content) > Unit 3

Lesson 11: Interpreting linear functions and equations- Linear equations word problems: earnings
- Linear equations word problems: volcano
- Linear equations word problems: tables
- Linear graphs word problems
- Linear graphs word problem: cats
- Linear equations word problems: graphs
- Linear equations word problem: marbles
- Linear equations word problem: file transfer
- Linear equations word problems

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# Linear equations word problem: file transfer

Sal finds the y-intercept and the slope of a linear relationship representing a top secret file transfer. He then interprets what the y-intercept and the slope mean in that context.

## Want to join the conversation?

- I can't find a video to help me solve this. This is the video that popped up when I searched it,but it was no help.

A charity organization is having a fundraiser.P(n)models the fundraiser's profit (in dollars) if n tickets are sold. A negative profit means the expenses exceeded the income from tickets.

P(n)=70n−1500

What are the expenses of the fundraiser?(6 votes)- You are never going to find a video that exactly matches your problem. It is asking you to think about the equation and how it relates to income from the tickets, expenses and profits. The problem tells you the profit is negative if the income is not large enough. So, the expenses must be the part of the equation that would make the profit be negative, and the income is the portion of the equation that would increase the profits.

Do you think you can figure it out now?

Give it a try. Comment back if you are still stuck, but tell me what you think.(3 votes)

- Can you please make videos for non-linear functions, or have you already made that?(5 votes)
- Morgan,

You can search the site for quadratic equations. In general, I would expect you would find more regarding non-linear function under Geometry.(1 vote)

- Anumeha mows lawns. She charges an initial fee and a constant fee for each hour of work.

The variable fff models Anumeha's fee (in dollars) for working ttt hours.

f=6+12tf=6+12tf, equals, 6, plus, 12, t

What is Anumeha's initial fee?(1 vote) - I kinda get it but all the way(0 votes)
- May you please make more videos on linear functions? I need a lot of help. Somebody give me some videos to watch about slopes and linear graphs.(0 votes)

## Video transcript

- [Voiceover] Agent Hunt is
transferring classified files from the CIA mainframe
into his flash drive. This is the formula for
the size of the files on Agent Hunt's drive S,
measured in megabytes, as a function of time t, measured in seconds. Complete the following sentences with the appropriate missing values. When the transfer began, the drive had blank
megabytes of files on it. So, when the transfer began, that would be t equals zero. T equals zero was right
when the transfer began. So t equals zero. S of zero is going to be five times zero, five times zero plus 45, which of course is just
going to be equal to 45. And S is measured, and they tell us, measured in megabytes. So there were 45 megabytes of files on his drive before, or right when the transfer began. Then they say, every 10 seconds, every 10 seconds, an
additional blank megabytes are transferred into the drive. So every 10 seconds, how many? Well, one way to think about, there's a bunch of ways
you could think about this one is, we know that
there were 45 megabytes at time equals zero. Let's think about what
happens 10 seconds later. How many megabytes are in his drive? So we can say S of 10 is going to be five times 10 plus 45, which is equal to 50 plus 45. So, time equals zero
there were 45 megabytes and 10 seconds later there's now 50 plus 45 megabytes. So in 10 seconds an extra 50 megabytes are transferred into the drive. And that's expected,
because as t increases one, this function goes up by five, so if t increases by 10, this
is going to increase by 50. So for every 10 seconds you would have, 50 megabytes are
transferred into the drive. And you can test that more if you want. You can say okay, let's
go another 10 seconds. S of 20 seconds, that's going to be 5 times 20 plus 45, which is equal to 100 plus 45. So notice, when 10 seconds
have passed in time, when we've increased time by 10 seconds, we've increased memory, our
memory that we're using, the megabytes we're
using has increased by, has increased by, has increased by 50.