Let's solve each problem step by step, focusing on
finding unit rates — that is, determining how much of something happens per unit of time (like per minute or per hour). We'll convert the given rates to a common time unit (usually per hour) and then compute the final answer.
---
Problem 1
> Andrew works in an assembly line at a toy manufacturing factory. This morning, he assembled 3 toys in 30 minutes. Assuming he continues working at the same rate, how many toys can he assemble in an hour?
#### Step-by-step:
- He assembles
3 toys in 30 minutes.
- There are
60 minutes in an hour, so we need to find how many toys he makes in 60 minutes.
- Since 60 minutes is
twice 30 minutes, we double the number of toys:
$$
3 \text{ toys} \times 2 = 6 \text{ toys}
$$
✔ Answer: 6 toys
---
Problem 2
> José stuffs envelopes as a part-time job on weekends. He stuffs 24 envelopes in 20 minutes. If he continues to stuff envelopes at this constant rate, how many envelopes can he stuff per hour?
#### Step-by-step:
- He stuffs
24 envelopes in 20 minutes.
- First, find how many envelopes per
minute:
$$
\frac{24}{20} = 1.2 \text{ envelopes per minute}
$$
- Now multiply by 60 minutes in an hour:
$$
1.2 \times 60 = 72 \text{ envelopes}
$$
Alternatively, use proportion:
- 20 minutes → 24 envelopes
- 60 minutes → ? envelopes
$$
\frac{24}{20} = \frac{x}{60} \Rightarrow x = \frac{24 \times 60}{20} = 72
$$
✔ Answer: 72 envelopes
---
Problem 3
> A recycling plant processes $ \frac{1}{4} $ ton of paper every 3 minutes. If the plant operates at a constant rate, how many tons of paper does the recycling plant process in 1 hour?
#### Step-by-step:
- It processes $ \frac{1}{4} $ ton every 3 minutes.
- First, find how many 3-minute intervals are in 60 minutes:
$$
\frac{60}{3} = 20 \text{ intervals}
$$
- So, in one hour, it processes:
$$
20 \times \frac{1}{4} = \frac{20}{4} = 5 \text{ tons}
$$
✔ Answer: 5 tons
---
Problem 4
> Tyler conducted a scientific experiment by mixing 2 liquids. The temperature of the liquids rose 1.5 degrees in 4 minutes. Continuing at this rate, what would be the increase in the temperature of the liquid in 1 hour?
> Write your answer as a mixed number, simplified fraction, or an exact decimal.
#### Step-by-step:
- Temperature increases
1.5 degrees in 4 minutes.
- Find how many 4-minute intervals are in 60 minutes:
$$
\frac{60}{4} = 15 \text{ intervals}
$$
- So total increase in 1 hour:
$$
15 \times 1.5 = 22.5 \text{ degrees}
$$
Or using fractions:
- $ 1.5 = \frac{3}{2} $
- $ 15 \times \frac{3}{2} = \frac{45}{2} = 22.5 $
As a
mixed number: $ 22\frac{1}{2} $
✔ Answer: $ 22.5 $ or $ 22\frac{1}{2} $ degrees
---
✔ Final Answers:
1.
6 toys
2.
72 envelopes
3.
5 tons
4.
$ 22.5 $ or $ 22\frac{1}{2} $ degrees
Let me know if you'd like these explained visually or with diagrams!
Parent Tip: Review the logic above to help your child master the concept of unit rates worksheet 7th grade.