Algebra 1 : Percent of Change
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Example Question #82 : How To Find The Percent Of Increase
If the number of Republican voters in a certain district has decreased from 150,000 to 78,560, what is the percent decrease in the number of Republican voters?
If the number of Republican voters in a certain district has decreased from 150,000 to 78,560, what is the percent decrease in the number of Republican voters?
To find the percent of decrease, we need to divide the difference by the original number:
So the number of Republican voters decreased by about
Example Question #91 : How To Find The Percent Of Increase
At a clothing store, a dress costs $79.99. After the dress was worn at a red carpet movie premiere, the clothing store decides to up the price of the dress to $119.99. What is the percent change in the price of the dress?
The percent change formula is new amount minus old amount then divided by old amount and multiplied by 100. In this case the formula should be
The price of the dress increased by 50%
Example Question #91 : How To Find The Percent Of Increase
Megan enrolled in a college biology course and received test grades of 63%, 80%, 42%, and 51%. Since she failed the course, she needed to retake it. This time, she received test grades of 80%, 91%, 84%, and 80%. What was the percentage change in her average test score from the first time she took the class to the second time? (Round your answer to the nearest whole percent)
The first step is finding the average test scores Megan received for each time she took the course. To find an average, add up all the scores and divide by the amount of scores.
For the first time she took the class the average is
For the second time she took the class the average is
Now, it is very important to understand that while her grade improved from 59% to 83.75% the difference between those two (24.75%) is not the percent change from her first score to the second. You still need to use the percent change formula of new amount subtracted by the old amount then divided by the old amount and multiplied by 100.
Rounded to the nearest whole percent this is 
Example Question #91 : How To Find The Percent Of Increase
At your job, you are currently making $10 an hour. Your boss says you are doing a great job and wants to give you a raise. You now make $12 an hour. Find the percent increase.
To find the percent increase, we use the formula
We know
so we can substitute into the equation. We get
Therefore, the percent increase is 20%.
Example Question #95 : How To Find The Percent Of Increase
A number five is increased to twelve. What is the percent increase?
Write the percentage increase or decrease formula.
If our final answer is a positive percentage, we will have a percent increase. Otherwise, a negative answer will indicate a percent decrease.
The original number is 5. The new number is 12. Substitute the numbers.
Simplify this expression.
This transition is a 
Example Question #96 : How To Find The Percent Of Increase
Last month you got paid $10 an hour at your job. You went under review this month, and they said they are increasing your pay to $12 an hour. Find the percent increase.
To find percent increase, we use the formula
We can substitute into the formula. We get
Therefore, the percent increase is equal to 20%.
Example Question #91 : How To Find The Percent Of Increase
The temperature on two consecutive days was 
To find the percent increase, we must find the amount that increased, divided by the original amount:
As a percent, we take this fraction and multiply by 100:
Example Question #98 : How To Find The Percent Of Increase
Last week, a gallon of milk cost $3.00. This week, the cost of a gallon of milk is $3.75. Find the percent increase.
To find the percent increase, we use the following formula:
Example Question #99 : How To Find The Percent Of Increase
Last month at your job, you were paid $10 an hour. This month, you received a raise and now earn $13 an hour. Find the percent increase.
To find the percent increase, we will use the following formula:
Therefore, the percent increase of your pay from last month to this month is 30%.
Example Question #100 : How To Find The Percent Of Increase
This week, a dozen eggs cost $5.40. Last week, a dozen eggs cost $4.50. Find the percent increase in price.
To find percent increase, we use the following formula:
Using the information given, we know the following:
so we can substitute these values into the formula. We get
Therefore, the percent increase in price is 
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