Question

solving problems involving percent change
find the percent change and tell whether it is a percent increase or a percent decrease.
1 original amount: 20
end amount: 15

3 original amount: 625
end amount: 550

5 original amount: 165
end amount: 222.75

7 original amount: 27
end amount: 38.661

8 original amount: 60
end amount: 70.02

9 how do you know when a situation involves a percent increase or a percent decrease?

Explanation:

Step1: Define percent change formula

Percent change = $\frac{\text{End amount} - \text{Original amount}}{\text{Original amount}} \times 100\%$

Step2: Calculate for 1

$\frac{15 - 20}{20} \times 100\% = -25\%$ → 25% decrease

Step3: Calculate for 2

$\frac{45 - 30}{30} \times 100\% = 50\%$ → 50% increase

Step4: Calculate for 3

$\frac{550 - 625}{625} \times 100\% = -12\%$ →12% decrease

Step5: Calculate for 4

$\frac{112 - 320}{320} \times 100\% = -65\%$ →65% decrease

Step6: Calculate for 5

$\frac{222.75 - 165}{165} \times 100\% = 35\%$ →35% increase

Step7: Calculate for 6

$\frac{423.80 - 326}{326} \times 100\% ≈29.99\%$ →29.99% increase

Step8: Calculate for 7

$\frac{3861 - 27}{27} \times 100\% = 13900\%$ →13900% increase

Step9: Calculate for 8

$\frac{70.02 - 60}{60} \times 100\% =16.7\%$ →16.7% increase

Step10: Determine increase/decrease rule

If end amount < original: decrease; else: increase

Answer:

1. 25% decrease
2. 50% increase
3. 12% decrease
4. 65% decrease
5. 35% increase
6. 29.99% increase
7. 13900% increase
8. 16.7% increase
9. Compare end amount to original: end < original → decrease; end > original → increase