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## 7th grade

### Course: 7th grade > Unit 4

Lesson 2: Constant of proportionality- Introduction to proportional relationships
- Identifying constant of proportionality graphically
- Constant of proportionality from graph
- Constant of proportionality from graphs
- Identifying the constant of proportionality from equation
- Constant of proportionality from equation
- Constant of proportionality from equations
- Constant of proportionality from tables
- Constant of proportionality from tables
- Constant of proportionality from table (with equations)
- Constant of proportionality from tables (with equations)

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# Constant of proportionality from tables

Identifying proportionality constants by looking at tables of values.

## Want to join the conversation?

- Hi! Here is some practice to help you succeed.

Which table has a proportionality of 3?

A

x y

1 2

2 3

3 4

4 5

B

x y

5 15

6 18

7 21

C

x y

1 5

3 15

5 25

Please upvote this so that others can practice too. If there are any problems, please notify me; I a just a learner like you.

Edit- Please do not read the comments until you answer the question. Have a good day!(47 votes)- if I'm allowed to answer its b if not then ill delete this right away(6 votes)

- i hate math. I know that's bad but is it ok even though i work?(7 votes)
- You shouldn't hate math because you think it is hard. Everything is hard when you are learning it. Think about other things you have learned to do that took some time. Believe it or not, math is actually quite easy. If you have the mindset that you are never going to finish something, you never will. You shoulkd stay positive. It's okay to not be perfect at some things, but that doesn't mean that you should give up because it's hard. I like to challenge myself to do things I think is hard. And if we praise students for speed or making things look easy, then the message we are sending them is: I’m only smart when I’m fast or when something is easy. A lot of students say they don’t like math because they are struggling. But you need math to live the rest of your life. If you need help, just ask. That's what Khan Academy was made for.(4 votes)

- once i watch the videos and then i go to a lesson i cant do it can someone help me😅(10 votes)
- I would watch the videos again and more carefully this time. Focus on equations and key words that Mr. Khan says.(5 votes)

- is there an easy way to do these?(7 votes)
- Why is the constant of proportionality represented as variable “k”. Can it be some other letter? Please help.(2 votes)
- It's really just a convention that everyone uses. Why everyone started using it, I don't know, but you could
**technically**use any other letter.(4 votes)

- what is 19+50?(3 votes)
- The answer is 69.(5 votes)

- How is c not the answer, 2/3 is o.6?(3 votes)
- 2/3 does not equal 0.6

0.6 = 6/10 = 3/5 once reduced.

If you convert 2/3 to a decimal, you will get 0.66666... It is a repeating decimal. You can't truncate the number if you need to maintain the fractions whole value.

Hope this helps.(4 votes)

- This stuff is easy how do you hate math! it's the best subject.(3 votes)
- Because not everyone thinks the same. Some have analytical brains while others have logical brains. Many of us are not blessed with the ability to understand or grasp the principles of math though we may do very well in other subjects.(4 votes)

- This is really easy to understand. Thank you!(3 votes)
- hey guys hows your day(3 votes)
- eh, can't complain. how is your day fella?(1 vote)

## Video transcript

- [Instructor] 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, so 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 x,y 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 not gonna be, is definitely not going to have a constant of proportionality of 0.6. And in fact, this table, this isn't even a
proportional relationship. For this first one, I would have to multiply by 7/4. And then here I'm going
to be multiplying by 10/6, which is equivalent to 5/3. And here I'm multiplying by 13/8, 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 four 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. Nine times 0.6, yeah, that is 5.4. Nine times six is 54. But now this is nine times 6/10. It's 54 divided by 10, which is 5.4. And now let's see, 14 times six is 84. So 14 times 6/10 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, three, to get to two we would
be multiplying by 2/3. And then here, once again,
we're multiplying by 2/3. And then here, once again,
we're multiplying by 2/3. So this is actually describing
a proportional relationship, but our constant of
proportionality here is 2/3, which, if you tried to
express it as a decimal, it would be 0.6 repeating. 2/3 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.