1. **State the problem:** A motorist travels from town X to town Z with stops and varying speeds, starting at 7:00am. We need to analyze the journey and represent it on a graph.
2. **Analyze the journey segments:**
- From X to Y: distance = 40 km, time = 1 hour, speed = 40 km/h.
- Rest at Y: 1 hour.
- From Y to Z: distance = 50 km, time = 1 hour, speed = 50 km/h.
- Rest at Z: 1 hour.
- Return from Z to X: speed = 30 km/h, distance = 90 km (40 + 50), time = distance/speed = $$\frac{90}{30} = 3$$ hours.
3. **Calculate timeline:**
- Start at 7:00am.
- X to Y: 7:00am to 8:00am.
- Rest at Y: 8:00am to 9:00am.
- Y to Z: 9:00am to 10:00am.
- Rest at Z: 10:00am to 11:00am.
- Z to X: 11:00am to 2:00pm.
4. **Define the function for distance from X over time:**
- From 7:00 to 8:00 (0 to 1 hour): distance increases from 0 to 40 km at 40 km/h.
- From 8:00 to 9:00 (1 to 2 hours): distance constant at 40 km (rest).
- From 9:00 to 10:00 (2 to 3 hours): distance increases from 40 to 90 km at 50 km/h.
- From 10:00 to 11:00 (3 to 4 hours): distance constant at 90 km (rest).
- From 11:00 to 14:00 (4 to 7 hours): distance decreases from 90 to 0 km at 30 km/h.
5. **Piecewise function for distance $d(t)$ where $t$ is hours after 7:00am:**
$$
d(t) = \begin{cases}
40t & 0 \leq t < 1 \\
40 & 1 \leq t < 2 \\
40 + 50(t-2) & 2 \leq t < 3 \\
90 & 3 \leq t < 4 \\
90 - 30(t-4) & 4 \leq t \leq 7
\end{cases}
$$
6. **Interpretation:** The graph of $d(t)$ vs $t$ shows the motorist's journey with increasing distance during driving periods and flat lines during rests.
Final answer: The motorist's journey is represented by the piecewise function above, starting at 7:00am and ending at 2:00pm after returning to town X.
Motorist Journey
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