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I have three word problems in this video.

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What I want to do in this video is not solve the word problems,

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but setup the equation that we could solve to get the answer to the word problem.

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What we are essentially going to do is setup the proportionality for the word problems.

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So In this 1st problem

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we have 9 markers cost $11.50. And then they ask:

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How much will 7 markers cost.

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Now, let's just set X to be equal to our answer, where X is equal to the cost of 7 markers.

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The way to solve a problem like this is to setup two

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ratios and set them equal to each other.

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So you could say that the ratio of 9 markers

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to the cost of 9 markers; 9/ 11.50 = 7/ X

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This is a completely valid proportion here.

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You could solve this to figure out how much those

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7 markers will cost.

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You could have 11.50/9 = X/7 .This is also a valid ratio.

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You could also think about ratios in other ways

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You could say, that the ratio of 9 markers to 7 markers,

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is going to be same as the ratio of their cost

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9/7 = 11.5/X or 7/9 = X/11.5

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So all of these would be valid proportion.

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Sp let's do this problem now. 7 aples cost $5.

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How much can I buy with $8.

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How many apples - let's call that X. We need to solve for X

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So we have the ratio between number

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of apples and cost of the apples - 7/5= X/8

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In this first situation the unknown was cost, in this example

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the unknown is number of apples.We can do all the different

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scenarios as above. we could say 7/X = 5/8

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Now lets do the last one. We have a cake recipe for

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5 people requires 2 eggs. How many eggs? So we want to know how many eggs?

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We will call how many eggs, which we

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need to find out as X, we can call it anything Y,A,B,C anything.

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So you could say the ratio of people to eggs is constant.

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We have 5 people for 2 eggs - 5/2 = 15/X

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Or you could say the ratio between 5/15 = 2/X

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All of these we setup the proportion and we can

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solve for X and get the answer.