yego.me
💡 Stop wasting time. Read Youtube instead of watch. Download Chrome Extension

Interpreting graphs of proportional relationships | 7th grade | Khan Academy


2m read
·Nov 11, 2024

  • [Instructor] We are told the proportional relationship between the number of hours a business operates and its total cost of electricity is shown in the following graph. All right. Which statements about the graph are true? Choose all answers that apply. So pause this video and see if you can figure this out.

All right, now let's do this together. And before I even look at the choices, let me analyze this a little bit. It is a proportional relationship. So we know that our total cost, let me write it here, our total cost is going to be equal to some constant of proportionality times our number of hours.

And we can even figure out what that constant of proportionality is going to be, because they give us this point A. We know that when our hours are four, so when this is four right over here, our total cost is $120. $120. So what times four is equal to 120? Well, we know that this k must be 30, 'cause 30 times four is 120.

So we can write that proportional relationship where our total cost is going to be equal to our constant of proportionality, 30, times our number of hours. Number of hours. So let's see which of these choices, and it might be more than one, say this or describe what's going on here.

So choice A, the y-coordinate of point A, so point A is at the point four comma 120, so the y-coordinate is the 120. That's the total cost when you run your business for four hours. The y-coordinate of point A represents the total cost of electricity when the business operates for four hours. Yes, that is exactly or very close (laughs) to what I just said, so I like this one.

The total cost of electricity is $35 when operating the business for one hour. So let's go to one hour here. This is going to be the total cost. Now, you might say, hey, this looks kinda close to $35, but that's why it was useful for us to write this relationship right over here, because what we see is that our total cost is going to be 30 times our number of hours.

Our total cost here is actually going to be 30, not 35. And it actually does look smack dab in between 20 and 40 versus a little bit closer to 40. So this one is not going to be true. And we're not gonna select none of the above, 'cause we actually did select one of the above. And we're done.

More Articles

View All
Why is the tech industry in the SF Bay Area?
Is there a specific reason, or was there specific events that occurred which has created this strength or grip that the Bay Area has when it comes to technology? I don’t think it is a path dependent history. In other words, I don’t think that Silicon Vall…
Types of forces and free body diagrams | AP Physics 1 | Khan Academy
In this video, we’re going to discuss different types of forces, but we’re going to do it in the context of free body diagrams. So let’s say that I have a table here, and I have a block that is sitting stationary on that table. What are all of the forces …
A day in a life of someone who is taking a break from med school during Covid in Japan Vlog🇯🇵📸
Hi guys! Today I’m going to be showing you guys what my typical day in Japan looks like. At my grandparents’ house, breakfast is at 7 a.m., so I wake up at 6:50. This is literally me in the morning. My grandpa prepares breakfast for us. I can’t imagine a …
Internet 101 | National Geographic
(light music) [Narrator] Today, about 4.2 billion people have access to a world of information never before seen. Such an extraordinary level of connectedness has revolutionized everything. From science and technology to commerce and romance, and virtual…
How to Talk to Aliens
[Michael] Where is everyone? We have been listening for messages from outer space for more than half a century, and so far… silence. Why? Are we truly alone in the universe? Or is everyone else acting like us and just doing a lot of listening? Maybe we ne…
Electromagnetism 101 | National Geographic
[Instructor] Electromagnetism or the electromagnetic force is one of the four fundamental forces of nature. It generates light and energy and holds atoms, matter, and the world as we know it together. Electromagnetism is a branch of physics that studies…