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## Comparing negative numbers

## Video transcript

John is making pasta dough. To make the dough, he
mixed 3/2 cups wheat flour with 3/4 cups regular
flour in some water. Write an inequality to
express the relationship between the wheat flour
and the regular flour. He mixed 3/2 cups
of wheat flour. 3/2 is the exact same
thing as 1 and 1/2, if we were to write
it as a mixed number. So it's more than 1
cup of wheat flour. And he mixes his that with
3/4 cups of regular flour. Well, 3/4 is less than 1, so 3/2
is definitely greater than 3/4. And we can just pick greater
than right over there. 3/2 is greater than 3/4. Let's do a couple more of these. One of the deepest points
in the Indian Ocean, the Diamantina trench, is
at negative 8 kilometers. We say it is
negative 8 kilometers because it is 8 kilometers
below sea level. The deepest part of the Bering
Strait is at negative 5 and 4/9 kilometers. Write an inequality to show the
relationship between these two points, and determine
which point is deeper. Let's see. We have a greater
than sign here. So we want to write
whichever quantity is greater on the
left-hand side. We look right over here. This number, negative 5 and
4/9, it is less negative. So it's actually going
to be greater value. It's not as deep. We can write negative
5 and 4/9 kilometers is greater than
negative 8 kilometers. And so if we're thinking
about which point is deeper, it's going to be the one that's
more negative, because that tells us how far below
sea level we are. So the negative
8 kilometer point is further below sea level. Let's see. Negative 8 kilometers. The Diamantina trench
at negative 8 kilometers is the deeper point. This is fun, because in
some of these questions you actually learn things. I always thought that the
deepest part of the Bering Sea-- well, anyway. We can talk about
that another time. Negative 8 kilometers, so the
Diamantina trench is deeper. Let's do one more. John is making noodles. To make the batter, he mixes
11/16 cups tapioca flour with 3/8 rice flour
and some water. Write an inequality to
express the relationship between the tapioca
flour and rice flour. So we're really comparing
11/16 cups of tapioca to 3/8 cups rice flour. So we're really comparing
these two fractions. And at first it might
seem hard to compare. You have different denominators. But 3/8 could easily be
converted to a fraction with 16 as the denominator. What would you do? Well, if you doubled
both the 3 and the 8-- you have to do the same
thing to the numerator and the denominator--
this fraction 3/8 is equivalent to 6/16. And then you would have
the same denominator. You could compare 11/16 to 6/16. Well, if you have
the same denominator and this numerator is
greater, 11 is greater than 6, 11/16 is going to be
greater than 6/16, which is the same thing as 3/8. And we got it right.