A hollow hemisphere bowl has an external radius of 21 cm and an internal radius of 17.5 cm. If the density of the material is 9.3 g/cm³, calculate the mass of the bowl.

The formula for the volume of a hemisphere is $V = \frac{2}{3}\pi r^3$.
Given external radius $R = 21 \text{ cm}$.

$$V_{ext} = \frac{2}{3}\pi (21 \text{ cm})^3$$ $$V_{ext} = \frac{2}{3}\pi (9261 \text{ cm}^3)$$ $$V_{ext} = 6174\pi \text{ cm}^3$$

Given internal radius $r = 17.5 \text{ cm}$.

$$V_{int} = \frac{2}{3}\pi (17.5 \text{ cm})^3$$ $$V_{int} = \frac{2}{3}\pi (5359.375 \text{ cm}^3)$$ $$V_{int} = \frac{10718.75}{3}\pi \text{ cm}^3$$

The volume of the material is the difference between the external and internal volumes.

$$V_{material} = V_{ext} - V_{int}$$ $$V_{material} = 6174\pi \text{ cm}^3 - \frac{10718.75}{3}\pi \text{ cm}^3$$ $$V_{material} = \left( \frac{18522 - 10718.75}{3} \right)\pi \text{ cm}^3$$ $$V_{material} = \frac{7803.25}{3}\pi \text{ cm}^3$$ $$V_{material} \approx 2601.0833 \pi \text{ cm}^3$$ $$V_{material} \approx 8171.09 \text{ cm}^3$$

The formula for mass is $M = \rho \times V$.
Given density $\rho = 9.3 \text{ g/cm}^3$.

$$M = 9.3 \text{ g/cm}^3 \times \frac{7803.25}{3}\pi \text{ cm}^3$$ $$M = 3.1 \times 7803.25 \pi \text{ g}$$ $$M = 24189.975 \pi \text{ g}$$ $$M \approx 75997.14 \text{ g}$$

There are 1000 grams in 1 kilogram.

$$M_{kg} = \frac{75997.14 \text{ g}}{1000}$$ $$M_{kg} \approx 75.997 \text{ kg}$$

Rounding to one decimal place:

$$M_{kg} \approx 76.0 \text{ kg}$$

The mass of the bowl is $\boxed{\text{76.0 kg}}$.

The movie lasted 2.3 hours.
This is 2 full hours and 0.3 of an hour.
To convert 0.3 hours to minutes:

$$0.3 \text{ hours} \times 60 \text{ minutes/hour} = 18 \text{ minutes}$$

So, the movie duration is 2 hours and 18 minutes.

The movie ended at 0110h (1:10 AM).
We need to subtract 2 hours and 18 minutes from 0110h.
First, subtract 2 hours:

$$0110\text{h} - 2\text{ hours} = 2310\text{h} \text{ (on the previous day)}$$

Now, subtract 18 minutes from 2310h:
We have 10 minutes, so we need to borrow 1 hour (60 minutes) from the hours.

$$23\text{h } 10\text{min} \rightarrow 22\text{h } (60+10)\text{min} = 22\text{h } 70\text{min}$$ $$22\text{h } 70\text{min} - 18\text{min} = 22\text{h } 52\text{min}$$

So, the start time is 2252h.

The time on Ali's watch when the movie started was $\boxed{\text{2252h}}$.