Video Transcript
Let’s talk about converting
fractions to percents. The word “percent” literally can be
translated “per hundred” or “per one hundred”.
We know that fractions represent a
part of a whole. The first thing that we’ll need to
convert a fraction to a percent is a denominator of one hundred. Whatever number is in the numerator
position, when the denominator is one hundred, is the percent. We represent a percent with this
symbol. So if we had seventeen out of one
hundred, we have seventeen percent.
Here’s an example of something you
might see: Convert seventy-seven hundredths to a percent. Because we know that a present is
the numerator over one hundred, we can easily recognize that this is seventy-seven
percent.
But sometimes we’ll need to convert
something that’s in a slightly different format.
Here’s an example that says:
Convert fourteen-tenths to a percent. Remember that our goal is to have a
part over the whole with the denominator of one hundred. So we need to think of a way to get
fourteen-tenths converted into a fraction of something over one hundred. When you copy down the problem, you
might recognize that it’s very easy to get from ten to one hundred. If we multiply the denominator of
ten by ten, we come up with one hundred. But if we’re going to work with
fractions, we always have to keep them equivalent by multiplying the numerator and
the denominator by the same thing. Here that will mean we’ll multiply
fourteen by ten and ten by ten on the denominator. Once we’ve converted this into a
fraction with a denominator of one hundred, we take the numerator and that’s our
percent. One hundred and forty percent. One hundred and forty percent is
the final answer.
You might also see something that
looks like this: thirteen over forty equals some percent. Let’s start out by creating a new
problem. Now that we’ve set up the problem,
we know that we’re going to be looking for some numerator over one hundred and I’m
gonna call that 𝑝. If we solve this equation for 𝑝,
that will be our percent. If we multiply both sides by one
hundred, we can get our percent 𝑝 by itself. I just did a little simplifying
here. So now we have our percent equals
one hundred and thirty over four. But this format is not super
helpful. When we deal with percents, we
usually want to have them in a decimal format. So I really wanna know what is one
hundred and thirty divided by four. When you do that division, you get
thirty-two and a half. So our percent equals thirty-two
and a half. And thirty-two and a half percent
is our final answer.
Here’s another example:
Four-sevenths equals what percent. We set up our problem in the same
way four-sevenths equals some number over one hundred. Multiply both sides by one hundred,
and then we get four hundred sevenths equals 𝑝. But 𝑝 equal to four hundred
sevenths is not super helpful. So we wanna actually do a division
here and find out what the decimal representation is. When you do that division, you’re
going to get an interesting answer. What should we do with a number
like this? We really have two choices
here. We can round the answer and find an
estimated percent, or we can use division and then find the remainder. Let’s say you wanted to round, this
time, to the nearest tenth. You could then just say it’s
fifty-seven and one-tenth percent. That’s about the percentage. But let’s say you really needed a
precise answer. So we wanna do some division and
find the remainder. Here’s what I mean by that. We’re going to divide four hundred
by seven. I know that the first number is a
five because we do know that it’s going to be fifty-seven and some remainder. Okay. Since I know that it’s fifty-seven
with some reminder, I can look closely at the division problem and see that the
remainder is one. So the precise answer is
fifty-seven and one-seventh percent.
One final example: What percent of
the pizza did you eat if you ate two slices of this pizza? Well, this pizza has eight slices
and you ate two of them. Two-eighths is the fraction that
you ate. But another way to write that is
one over four. So if we look at one-fourth,
one-fourth is much easier to convert to a percent. In fact, you might even be able to
do this one in your head. So to get one-fourth into a
fraction out of one hundred, we multiply the top and bottom by twenty-five. And we know that one-fourth is then
twenty-five out of one hundred. And the final answer would be
twenty-five percent.
