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Answer: No, they do not form a proportion</h3>
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Explanation:
Your teacher is effectively asking "are the fractions 19/8 and 5/4 equal?"
Let's assume for now that they are. So we have 19/8 = 5/4
To check if that is a true equation, let's cross multiply
19/8 = 5/4
19*4 = 8*5
76 = 40
The last equation is not true, so the first equation is also not true. The ratios are not in proportion.
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Alternative method:
Instead of cross multiplying, we can get all the fractions to have the same denominator. The LCD (lowest common denominator) of the two given fractions is 8. Let's turn 5/4 into a fraction with 8 in the denominator.
We'll multiply top and bottom by 2 to get 5/4 turning into 10/8
Now we're asking "are 19/8 and 10/8 the same?" in which the answer is "no they are not the same". The numerators 19 and 10 are different. The fraction 19/8 is larger than 10/8. So 19/8 is larger than 5/4.
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2nd Alternative method:
Use your calculator to see that
19/8 = 2.375
5/4 = 1.25
The decimal values should be the same if the fractions were equal, but they are not. This is a very quick way to compare two fractions.
