ACT Math : Percent of Change
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Example Questions
Example Question #1 : Percent Of Change
A manager of a pizzeria has five people on his staff. Three are full-time staff, each of whom received a starting salary of $25,000 annually for 40 hours of work per week. Each year they have worked at the pizzeria, their pay increases by 7%. Sally has worked at the pizzeria for one year, Nancy for two years and John for three years. The other two employees are part-time and are paid $8.25 per hour. Irene works 1,000 hours per year and Andrew works 700 hours per year. What is the pizzeria’s cost per year for staff salaries?
$86,025
$94,397.50
$84,275
$96,872.50
$92,525.50
$94,397.50
It is important to remember that the employees who receive an annual increase (Sally, Nancy and John), receive the 7% increase based on the salary from the year before.
If you answered $89,025, you did not account for the 7% increase in salary for Nancy and John.
If you answered $89,525, you did not increase John's salary by 7% for the third year ($26,750 * 7% = $1,872.50 --- $1,872.50 + $26,750 = $28,622.50).
If you answered $91,275, you did not account for the 7% to be applied to John's second year salary; rather, you added the dollar increase ($1750) that he received between his first and second year and added it to his second year salary.
If you answered $93,872.50, you accounted for both part-time employees working 1,000 hours. Therefore, the correct answer is $94,397.50.
Example Question #1 : Percent Of Change
Ben and Sam have a furniture design business. The first year they earn $10,000 in profits. The second year they earn $12,000 in profits. What is the percentage increase in profit between year one and two?
12%
10%
20%
25%
2%
20%
Percentage Increase = (Year Two Profit – Year One Profit) / Year One Profit
= ($12,000 - $10,000) / $10,000 = $2000 / $10,000 = .2 = 20%
Example Question #1 : Percent Of Change
Truck A has a length of 8'3" (8 ft. and 3 inches). Truck B has a length of 14'5".
What is the percentage increase in length going from Truck A to Truck B?
74.74
79.11
35.42
66.53
74.74
Find a common unit—in this case it is inches. The increase is from 99” to 173”. To find the percentage increase we find the difference and then divide by the length of Truck A.
or 74.74%
Example Question #2 : How To Find The Percent Of Increase
Danielle has two jobs. Her retail job pays her $8.50 per hour and she works 20 hours per week in that job. Her office job pays her $12 per hour and she works 15 hours per week in the office. If she starts working an extra 10 hours a week at her office job, what is her percentage increase in total weekly pay? Round to one decimal point.
33.4%
40.0%
25.7%
22.9%
34.3%
34.3%
Pay = Hours worked x Rate per hour
Retail job = 20 x $8.50 = $170.00
Office job = 15 x $12.00 = $180.00
Current weekly pay = $170.00 + $180.00 = $350.00
Additional Office job hours = 10 x $12.00 = $120.00
Percentage Increase = $120 / $350 = .343 (rounded) --> 34.3%
Example Question #2 : Percent Of Change
A university has 
To find the percentage increase, use the following formula:
Increased # of students this year / # of students last year
If there were 
Therefore:
The number of students increased by 
Example Question #5 : Percent Of Change
Thurman is given 
It will decrease over time.
It will increase exponentially over time.
It will first decrease, then increase.
It will increase linearly over time.
It will remain the same over time.
It will decrease over time.
To find out which option is correct, simply follow one complete cycle (that is to say, one day's worth of actions).
We will use 
So, after each cycle, the total amount of money decreases by 
Example Question #5 : How To Find The Percent Of Increase
On a given day, the temperature ranges from a low of 
To find percent change, subtract the "old" amount from the "new" amount, then divide the result by the "old" amount. The result is a percent increase if positive and a percent decrease if negative.
Thus, there was a 
Example Question #1 : Percent Of Change
What is the percent increase from 
To find percent change, subtract the "old" amount from the "new" amount, then divide the result by the "old" amount. The result is a percent increase if positive and a percent decrease if negative. In this case, don't forget 
Example Question #5 : Percent Of Change
The price of a particular metal raises from 
To find percent change, subtract the "old" amount from the "new" amount, then divide the result by the "old" amount. The result is a percent increase if positive and a percent decrease if negative.
Example Question #6 : How To Find The Percent Of Increase
A particular stock gains 
To find percent change, subtract the "old" amount from the "new" amount, then divide the result by the "old" amount. The result is a percent increase if positive and a percent decrease if negative. In this case, to keep our amount constantly compared to Tuesday, set Tuesday's price as a variable.
Thus, our final gain relative to Tuesday is 
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