1. **Stating the problem:**
We have an original cube with volume $V = 7 \times 7 \times 7 = 343$ cm$^3$.
We want to find the final surface area, final volume, scale factor $k$, and final volume in ft$^3$ after scaling.
2. **Understanding volume and surface area scaling:**
If a shape is scaled by a linear factor $k$, then:
- Surface area scales by $k^2$
- Volume scales by $k^3$
3. **Given:**
The linear scale factor is $\frac{7}{5}$.
4. **Calculate final surface area:**
Original surface area of a cube with side length $7$ cm is:
$$S = 6 \times 7^2 = 6 \times 49 = 294 \text{ cm}^2$$
Final surface area:
$$S_F = S \times \left(\frac{7}{5}\right)^2 = 294 \times \frac{49}{25}$$
Calculate intermediate step:
$$294 \times \frac{49}{25} = \frac{294 \times 49}{25}$$
Calculate numerator:
$$294 \times 49 = 14406$$
So:
$$S_F = \frac{14406}{25} = 576.24 \text{ cm}^2$$
5. **Calculate final volume:**
Original volume:
$$V = 343 \text{ cm}^3$$
Final volume:
$$V_F = V \times \left(\frac{7}{5}\right)^3 = 343 \times \frac{343}{125}$$
Calculate intermediate step:
$$343 \times \frac{343}{125} = \frac{343 \times 343}{125}$$
Calculate numerator:
$$343 \times 343 = 117, 649$$
So:
$$V_F = \frac{117,649}{125} = 941.192 \text{ cm}^3$$
6. **Calculate scale factor $k$:**
$$k = \frac{7}{5} = 1.4$$
7. **Convert final volume to ft$^3$:**
Since $1$ ft = $30.48$ cm, then
$$1 \text{ ft}^3 = 30.48^3 = 28,316.85 \text{ cm}^3$$
Convert:
$$V_F = \frac{941.192}{28,316.85} = 0.0332 \text{ ft}^3$$
**Final answers:**
- Surface Area Final = $576.24$ cm$^2$
- Volume Final = $941.192$ cm$^3$
- Scale factor $k = 1.4$
- Volume Final in ft$^3 = 0.0332$ ft$^3$
Cube Scaling 4Ce463
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