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### Course: Pre-algebra>Unit 9

Lesson 3: Compare and interpret constants of proportionality

# Comparing constants of proportionality

Working example comparing constants of proportionality.

## Want to join the conversation?

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

If there are any problems, please notify me; I a just a learner like you.

• Is it b?
• why is it 1 cupcake for \$2? if d=2c. wouldn't it be 2 cupcakes for \$1? we could assume the is a 1 before the d, so 1d=2c.
• The coefficient of "d" is 1. But that doesn't tell you that there is d=\$1 when c=2 cupcakes. use the equation. If c=2 cupcakes, then: d = 2(2) = 4
So 2 cupcakes costs \$4. The ratio of 1 cupcake to \$2 if you reduce the ratio.

Hope this helps.
• Wouldn't D=0.75S mean that it's one dollar for .75 o a scoop? Or 1.25 for one scoop? Help!
• I think you might be confusing a variable with a unit. For example, when we use m to represent meters, you would write 10 m if something was 10 meters long. D does not represent the unit, or word, dollars. It represents a quantity in number of dollars. S doesn't represent the unit, or word, scoop. It represents a quantity in number of scoops. When you read D = 0.75 S, you should say something like, the cost in dollars is equal to 0.75 times the number of scoops. I think you might be reading it as one dollar (1D, or just D) is equal to 0.75 scoops. I'm not sure where you got \$1.25 for one scoop from. Perhaps you just added \$0.25 to each side. However, if the ice cream was \$1 for 0.75 scoops, you could multiply each amount by 4/3 to calculate the unit rate per scoop. I hope this helps.
• Store A is the correct answer, right?
• By the way, there is a very easy way to know your nine multiplication problems. All you have to do is put down the finger on your hand that your multiplying by Here is an example 9 times 6 I'm going to hold up all ten fingers and then put down my sixth finger on the right of the finger you have 5 on the other side you have 4 put 5 and 4 together you have 54 which is your answer or you can just memorize you multiplication problems but I'm not very good at that.
• Sal: "one point half"
Me: "I love these videos."
Oh Sal, you slay me. I shall remember the one point half. :))))))))_))_)_
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• Yes indeed it is a great place for education quality improvement
(1 vote)
• I'd rather the scoops be good than cheap.