640 for 8 hours, 240 boys in 6 groups, 108 points 13 games, 480 words per 80 minutes, 25 calls per shoot, 960 for 80 pigs, 120 per 12 buckets of beans, 63 pages for 9 minutes

\frac{$640}{8 \text{ hours}} = $80/\text{hour} The rate is \boxed{80/hour}$.

2) Rate for 240 boys into 6 groups

$$\frac{240 \text{ boys}}{6 \text{ groups}} = 40 \text{ boys/group}$$

The rate is $\boxed{40 \text{ boys/group}}$.

3) Rate for 108 points in 13 games

$$\frac{108 \text{ points}}{13 \text{ games}} \approx 8.31 \text{ points/game}$$

The rate is approximately $\boxed{8.31 \text{ points/game}}$.

4) Rate for 480 words per 80 minutes

$$\frac{480 \text{ words}}{80 \text{ minutes}} = 6 \text{ words/minute}$$

The rate is $\boxed{6 \text{ words/minute}}$.

5) Rate for 250 calls per 5 hours

$$\frac{250 \text{ calls}}{5 \text{ hours}} = 50 \text{ calls/hour}$$

The rate is $\boxed{50 \text{ calls/hour}}$.

6) Rate for $960 for 80 pigs

\frac{$960}{80 \text{ pigs}} = $12/\text{pig} The rate is \boxed{12/pig}$.

7) Rate for 120 per 12 buckets of beans

$$\frac{120}{12 \text{ buckets}} = 10/\text{bucket}$$

The rate is $\boxed{10/\text{bucket}}$.

8) Rate for 63 pages for 9 minutes

$$\frac{63 \text{ pages}}{9 \text{ minutes}} = 7 \text{ pages/minute}$$

The rate is $\boxed{7 \text{ pages/minute}}$.