Let's solve each problem step by step, using the appropriate method as requested (tape diagrams, tables, or direct calculation). The main concept is
finding the whole amount when given a part and a percent.
---
1) Use a tape diagram to solve the problem.
> Jan saved $15 on a jacket that was on sale for 20% off. What was the original price of the shirt?
Step-by-step:
- A 20% discount means Jan saved 20% of the original price.
- So, $15 = 20% of the original price.
- We can use a
tape diagram to represent the whole (original price) divided into 10 equal parts (since 20% = 2/10).
- Each part represents 10%, so 2 parts = 20% = $15.
- Therefore, 1 part = $15 ÷ 2 = $7.50
- Total (10 parts) = 10 × $7.50 =
$75
✔ Answer: $75
Tape Diagram (visual representation):
```
[ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ]
10% 10% 10% 10% 10% 10% 10% 10% 10% 10%
↑ ↑
$7.50 $7.50
```
2 parts = $15 → 10 parts = $75
---
2) Use a table to solve the problem.
> John chewed 2 pieces of bubble gum. If this was 40% of his gum, how much gum did he have?
We’ll use a
ratio table:
| Chewed | Percent |
|--------|---------|
| 2 | 40% |
| ? | 100% |
We want to find the total number of pieces (whole) such that 40% = 2.
Set up proportion:
$$
\frac{2}{x} = \frac{40}{100}
$$
Cross-multiply:
$$
40x = 200 \Rightarrow x = 5
$$
✔ Answer: 5 pieces of gum
Table filled in:
| Chewed | Percent |
|--------|---------|
| 2 | 40% |
| 5 | 100% |
---
3) Six is 80% of what number?
Let the unknown number be $ x $.
So:
$$
6 = 0.80x
$$
Divide both sides by 0.80:
$$
x = \frac{6}{0.80} = 7.5
$$
✔ Answer: 7.5
---
4) Jose got 7 questions right on his test. If his grade was 70%, how many questions were on the test?
Let total number of questions be $ x $.
70% of $ x $ = 7
$$
0.70x = 7 \Rightarrow x = \frac{7}{0.70} = 10
$$
✔ Answer: 10 questions
---
5) Blake received 120 votes for student body president. If this was 50% of the votes, how many students voted?
50% = half, so:
$$
\text{Total votes} = 120 \times 2 = 240
$$
Or:
$$
0.50x = 120 \Rightarrow x = \frac{120}{0.50} = 240
$$
✔ Answer: 240 students voted
---
6) Fifteen is 75% of what number?
Let $ x $ be the number:
$$
0.75x = 15 \Rightarrow x = \frac{15}{0.75} = 20
$$
✔ Answer: 20
---
7) Two of the pets at the pet store are birds. If this is 10% of the pets at the store, how many pets are at the store?
Let total number of pets = $ x $
$$
10\% \text{ of } x = 2 \Rightarrow 0.10x = 2 \Rightarrow x = \frac{2}{0.10} = 20
$$
✔ Answer: 20 pets
---
✔ Final Answers Summary:
1) $75
2) 5 pieces
3) 7.5
4) 10 questions
5) 240 students
6) 20
7) 20 pets
Let me know if you'd like visual tape diagrams or tables drawn out!
Parent Tip: Review the logic above to help your child master the concept of finding the whole given a part and a percent worksheet.
