Exercise 2 solution (Python)

def naismith(km, ascent_m):
    return km / 5 * 60 + ascent_m / 10

def clock(minutes):
    return f"{int(minutes // 60):02d}:{int(round(minutes % 60)):02d}"

legs = [("Car park to bridge", 1.5, 40, 80),
        ("Bridge to col", 2.5, 260, 35),
        ("Col to summit", 1.0, 190, 120),
        ("Summit to car park", 5.0, 0, 200)]

t = 9 * 60
print("Start", clock(t))
for name, km, ascent, bearing in legs:
    t += naismith(km, ascent)
    print(f"{name}: {km} km, {ascent} m up, bearing {bearing}, arrive {clock(t)}")

Output:
Start 09:00
Car park to bridge: 1.5 km, 40 m up, bearing 80, arrive 09:22
Bridge to col: 2.5 km, 260 m up, bearing 35, arrive 10:18
Col to summit: 1.0 km, 190 m up, bearing 120, arrive 10:49
Summit to car park: 5.0 km, 0 m up, bearing 200, arrive 11:49

Total: 10 km and 490 m of ascent, 169 minutes of moving time. These are moving times only: add breaks and a safety margin (see the notes on the chapter page), and write the finish time on the card as an estimate, not a promise.