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Equivalent fraction word problem example 2

Video transcript

Mary wants the fraction of pink blocks in model B to be equivalent to the fraction of pink blocks in model A. How many blocks in model B need to be pink in order to make that happen? So let's look at model A. So how many equal sections are there? There's 1, 2, 3, 4, 5 equal sections. There are 5 equal sections. And what fraction of them are pink? Well, you have one of them is pink. One of the blocks is pink. So 1/5 of the blocks over here in model A is pink. Now, we have to think about how to make 1/5 pink right over here. So let's think about it. So how many, first of all, total blocks are there? There's 1, 2, 3-- let me actually do this in another color. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20. There are 20 total blocks here. And you see that this is the exact same length. Model B is the exact same length as model A. And so for every block that you have in model A, for every block here, you must have 4 in model B because we went from 5 sections to 20. So we're essentially multiplying by 4. And you even see it here. If we were to just draw a line right down here you see, you see for every block in model A, you have 1, 2, 3, 4 blocks in model B. So one block in model A that is pink would be the same thing as 4 blocks in model B. We would literally just multiply this times 4. So 4 of the 20 will need to be made pink, so 1, 2, 3, 4. And you see that it exactly matches up. This is the exact same fraction of the entire model over here. So when they say how many blocks in model B need to be pink to make that happen? It would be 4.