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2 / 6 yellow => convert such
that it has a denominator of 12 => 2 / 6 x 2 / 2 = 4 / 12

5 / 12 blue

3 / 12 green

Ranking:

1.
5 / 12 blue

2.
4 / 12 yellow

3.
3 / 12 green

Conclusion: the
amount of yellow chalk (4 / 12) is greater than the amount of green chalk (3 /
12) in the bucket

Blue is 5 / 12 of the bucket
which is less than ½ of the chalk in the bucket. We should remember that there
are 12 chalks (5 blue + 4 blue + 3 green) in the bucket and that ½ of this is 6
(12 x ½). We can therefore say that 5 blue chalks are less than 6 chalks, which
is the exact half of the bucket of chalks. Therefore Andrea is correct and Michelle is incorrect.

Please let me know if you need any clarification. I'm always happy to answer your questions.