Let's solve each problem step by step. The goal is to
find the final amount after a percentage increase or decrease.
We use the following formulas:
-
Increase:
$$
\text{Final Amount} = \text{Original Amount} + (\text{Original Amount} \times \frac{\text{Percentage}}{100})
$$
-
Decrease:
$$
\text{Final Amount} = \text{Original Amount} - (\text{Original Amount} \times \frac{\text{Percentage}}{100})
$$
Alternatively, you can use:
- Increase: $ \text{Final} = \text{Original} \times (1 + \frac{\text{Percent}}{100}) $
- Decrease: $ \text{Final} = \text{Original} \times (1 - \frac{\text{Percent}}{100}) $
---
1) Increase $200 by 50%
$$
200 \times (1 + 0.50) = 200 \times 1.50 = 300
$$
✔ Answer: $300
---
2) Decrease $300 by 50%
$$
300 \times (1 - 0.50) = 300 \times 0.50 = 150
$$
✔ Answer: $150
---
3) Increase 160 yards by 10%
$$
160 \times (1 + 0.10) = 160 \times 1.10 = 176
$$
✔ Answer: 176 yards
---
4) Decrease 400 miles by 30%
$$
400 \times (1 - 0.30) = 400 \times 0.70 = 280
$$
✔ Answer: 280 miles
---
5) Increase $130 by 10%
$$
130 \times 1.10 = 143
$$
✔ Answer: $143
---
6) Increase 6 inches by 100%
A 100% increase means doubling:
$$
6 \times (1 + 1.00) = 6 \times 2 = 12
$$
✔ Answer: 12 inches
---
7) Decrease 20 ounces by 25%
$$
20 \times (1 - 0.25) = 20 \times 0.75 = 15
$$
✔ Answer: 15 ounces
---
8) Decrease 50 miles by 100%
100% decrease means it becomes zero:
$$
50 \times (1 - 1.00) = 50 \times 0 = 0
$$
✔ Answer: 0 miles
---
9) Increase 150 yards by 10%
$$
150 \times 1.10 = 165
$$
✔ Answer: 165 yards
---
10) Decrease $350 by 40%
$$
350 \times (1 - 0.40) = 350 \times 0.60 = 210
$$
✔ Answer: $210
---
11) Increase 15 gallons by 30%
$$
15 \times 1.30 = 19.5
$$
✔ Answer: 19.5 gallons
---
12) Decrease 256 pints by 25%
$$
256 \times (1 - 0.25) = 256 \times 0.75 = 192
$$
✔ Answer: 192 pints
---
13) Decrease $1270 by 50%
$$
1270 \times 0.50 = 635
$$
✔ Answer: $635
---
14) Increase 40 inches by 25%
$$
40 \times 1.25 = 50
$$
✔ Answer: 50 inches
---
15) Increase 25 inches by 40%
$$
25 \times 1.40 = 35
$$
✔ Answer: 35 inches
---
✔ Final Answers Summary:
| Problem | Answer |
|--------|--------|
| 1 | $300 |
| 2 | $150 |
| 3 | 176 yards |
| 4 | 280 miles |
| 5 | $143 |
| 6 | 12 inches |
| 7 | 15 ounces |
| 8 | 0 miles |
| 9 | 165 yards |
| 10 | $210 |
| 11 | 19.5 gallons |
| 12 | 192 pints |
| 13 | $635 |
| 14 | 50 inches |
| 15 | 35 inches |
Let me know if you'd like this in a printable format or with working-out steps filled in!
Parent Tip: Review the logic above to help your child master the concept of percentage increase and decrease worksheet pdf.
