Question 47·Medium·Percentages
A factory produced 1,350 units in January and 1,620 units in February. By what percent did production increase from January to February?
For percent increase or decrease questions, always follow the same template: (1) subtract to find the change, (2) divide by the original amount (the starting value), and (3) multiply by 100 to convert to a percent. On the SAT, quickly label which number is “original” to avoid accidentally using the final value in the denominator, and simplify fractions like by canceling common factors to keep arithmetic fast and accurate.
Hints
Find the increase in units
First, subtract January’s production from February’s production to find how many more units were made.
Decide which month is the “original”
Percent increase is based on where you started. Which month’s production should be in the denominator: January or February?
Use the percent increase formula
Use and plug in the increase and January’s production.
Simplify the fraction
Simplify before multiplying by 100 to make the calculation easier.
Desmos Guide
Compute the percent increase directly
In Desmos, type the expression (1620 - 1350)/1350 * 100. The calculator will output a number; interpret this value as the percent increase from January to February.
Step-by-step Explanation
Identify the change in production
Find how many more units were produced in February than in January.
So the production increased by 270 units.
Recall the percent increase formula
Percent increase compares the change to the original amount (January):
Here, the original amount is January’s production, .
Compute the percent increase
Plug the numbers into the formula:
Simplify by dividing both numerator and denominator by :
Now convert to a percent:
So the production increased by percent from January to February.