Linear Relationships % increase & % decrease LESSON 7.4(D)

PERCENT CHANGE​ (a)  

• the amount that a quantity increases or decreases

• the rate at which a quantity changes over time

• the difference between two quantities

Answer explanation

The correct answer is the amount that a quantity increases or decreases, as percent change represents the relative increase or decrease in a quantity.

How to find percent change ​ (a)  

• by subtracting

• by multiplying

• by dividing

Answer explanation

To find percent change, you subtract the original value from the new value, divide by the original value, and then multiply by 100 to get the percentage change.

Find the percent of change by ​ (a)  

• using % proportion

• using $ proportion

• using * proportion

Answer explanation

The correct choice is using % proportion to find the percent of change.

Use a percent _​ (a)   to set up and solve the proportion

• bar diagram

• pie chart

• line graph

Answer explanation

To set up and solve a proportion, you would typically use a percent bar diagram, not a pie chart or line graph.

Bar diagram can be helpful when the question is not asking for a straight ​ (a)  

• % change

• Pie chart

• Line graph

Answer explanation

Bar diagram can be helpful when the question is not asking for a straight % change.

A new restaurant has a staff of 20. The next year, the restaurant had 35 staff members. What was the percent increase from the first year to the second?

• 50%

• 100%

• 25%

• 75%

Answer explanation

The percent increase from 20 to 35 staff members is calculated as (35-20)/20 * 100 = 75%. Therefore, the correct answer is 75%.

The number of wolves in Yellowstone National Park in 1980 was 192. By 1990, the population of wolves had increased by 25%. How many wolves were in Yellowstone in 1990?

• 240

• 180

• 220

• 210

Answer explanation

To find the number of wolves in Yellowstone in 1990, we first calculate 25% of 192 (192 * 0.25 = 48) and then add it to the initial population (192 + 48 = 240). Therefore, there were 240 wolves in Yellowstone in 1990.

A sweater costs $42. A week later it goes on sale for $31.50. What percent off is the sale?

• 15%

• 20%

• 25%

• 10%

Answer explanation

To calculate the percent off, find the difference between the original price ($42) and the sale price ($31.50), which is $10.50. Then, divide the discount amount by the original price ($10.50 / $42) and multiply by 100 to get 25% off.

 

Jason bought a jacket on sale for $36. If the jacket was on sale for 20% off, what was the original price of the jacket?

• $50

• $40

• $30

• $45

Answer explanation

To find the original price, we need to divide the sale price by (1 - discount percentage). $36 / (1 - 0.20) = $45. Therefore, the original price of the jacket was $45.