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

Constant of proportionality from tables | 7th grade | Khan Academy


2m read
·Nov 11, 2024

We are asked which table has a constant of proportionality between y and x of 0.6. Pause this video and see if you can figure that out.

All right, so just as a reminder, the constant of proportionality between y and x, one way to think about it is that y is equal to some constant times x. Y is proportional to x, and this constant right over here is our constant of proportionality. So if that's going to be 0.6, in our tables or in the table that has a constant of proportionality of 0.6, y should be equal to 0.6 times x for every xy pair.

So let's look at these choices. So is seven 0.6 times four? Well, no, seven is larger than four. 0.6 times four would actually be 2.4, so this one is definitely not going to have a constant of proportionality of 0.6. In fact, this table, this isn't even a proportional relationship, where for this first one I would have to multiply by seven-fourths, and then here I'm going to be multiplying by ten-sixths, which is equivalent to... and here I'm multiplying by 13 over eight. So I'm not multiplying by the same constant every time, so this isn't even a proportional relationship.

Now let's look at choice B. Well, to go from 4 to 2.4, that is, you would multiply by 0.6, but that's not enough for us to say that this is truly a proportional relationship. It would have to be 0.6 in every scenario. So let's see, 9 times 0.6... yeah, that is 5.4. 9 times 6 is 54, but now this is 9 times 6 tenths; it's 54 divided by 10, which is 5.4.

And let's see, 14 times 6 is 84, so 14 times 6 tenths would indeed be 8.4. So this looks like our choice, and we can verify that this would not be the case. Let's see, 3 to get to 2, we would be multiplying by two-thirds, and then here once again we're multiplying by two-thirds, and then here once again we're multiplying by two-thirds. So this is actually describing a proportional relationship, but our constant of proportionality here is two-thirds, which if you try to express it as a decimal would be 0.6 repeating. Two-thirds is equal to 0.6 repeating, and so it is proportional but does not have this constant of proportionality.

So we like our choice B.

More Articles

View All
Regional climates | Weather and climate | Middle school Earth and space science | Khan Academy
What’s the weather usually like in the winter where you live? If you asked someone in Fairbanks, Alaska, they might describe below-freezing days and navigating through huge drifts of snow. If you asked someone else in Miami, Florida, they might tell you t…
Thin-layer chromatography (TLC) | Intermolecular forces and properties | AP Chemistry | Khan Academy
So let’s say that I have a vial of some mystery liquid right over here, and I want to start figuring out what’s going on there. The first step is to think about, is it just one substance or is it a mixture of multiple substances? The focus of this video i…
Daily Live Homeroom With Sal: Wednesday, March 25
Hi everyone! Sal Khan here for our daily live stream. Just as a reminder of what this is for some of y’all who might be new: as the school closures have kind of rolled out around not just the country but the world, we realized that there’s a lot of demand…
Homeroom with Sal, Carol Dweck, PhD, & Vicky Colbert - Tuesday, May 25
Hi everyone, Sal Khan here from Khan Academy. Welcome to the Homeroom with Sal live stream. We have a very exciting show today. We have, I would say, two mega figures in the world of education. We have Carol Dweck, a professor at Stanford. You all might …
Stealth Wealth (Explained)
They say to live happy, live hidden. Something you’re not yet aware of is happening in the markets, and the implication it has will most likely impact you. Rich people are changing their behaviors to accommodate the current moment in time, and the average…
The One Ring Explained
These books are all about this ring. How it’s found and [spoiler alert] how it’s destroyed. While Tolkien built the largest and most consistent fictional universe, he sure didn’t mind being vague at times. So, if you finished the story and then thought: w…