Whitney categorized her spending for
this month into four categories.
Rent, food, fun, and other.
The percents she spent in
each category are pictured
below in the pie chart.
If Whitney spent a total
of $2,000 this month,
how much did she spend on food?
Looking at the pie chart,
notice how she spent 20%
of her money on food this month.
And therefore we want
to answer the question,
what is 20% of $2,000?
Now there are several ways
to answer this question.
But whenever we're trying
to find the percent
of a number, the easiest
way is to convert the
percent to a decimal and multiply.
The word of represents multiplication.
So because 20% as a decimal
would be 0.20, or just 0.2,
to find 20% of 2,000, we
would find the product
of 0.2 and 2,000.
Which equals 400.
Of course we can check
this on the calculator.
Point two times 2,000 is 400.
Which means she spent
$400 on food this month.
Notice how the dollar
sign is already here,
so we just enter 400.
Let's also show how to set this
up using a percent equation
and a percent proportion.
For the percent equation,
the word is means equals.
The word of means multiplication.
And the word what represents
the unknown, or the variable.
So for our percent equation,
because the first word is what,
we'd write down the
variable of the unknown,
which represents the amount
of money spent on food
this month, so let's use the variable f.
Is means equals.
20% as a decimal we know is 0.2.
Of means multiplication.
And then we have $2,000 or just 2,000.
And notice how this product is the same
as the product shown here,
which we already know is 400.
So of course, using the percent equation,
we get the same result.
Now let's also set this up
using our percent proportion.
For the percent proportion,
we can also use keywords.
We can write is over of equals p over 100.
Where p would be the percent.
We can also think of this as
the part compared to the whole
must equal the percent compared to 100.
So we know we'd have a proportion.
And because we're given
the percent as 20%,
this ratio here would be 20 to 100.
And then for this ratio
here, the part to the whole,
we're trying to determine
what part of the $2,000
she spent on food.
So the part is the unknown.
So the ratio of the part to
whole would be f over 2,000.
Now that we have our proportion,
we would cross multiply
and solve for f.
So f times 100 must equal 2,000 times 20.
Well f times 100 is 100f.
2,000 times 20 is equal to 40,000.
Divide both sides by 100.
Simplifying, we get f
equals, again 40,000 divided
by 100 is 400.
So regardless of method, of
course we get the same result.
Whitney spent $400 on food this month.
I hope you found this helpful.
