Variables and Types Practice

These questions follow Variables and Data Types and Input and Output. A variable is a name for a value; a type is what that value is allowed to do. Almost every early bug in this course is one of those two sentences being ignored.

Questions

1. Give the type — int, float, str, or bool — for each: the number of chairs in a room; the mass of a recycling bin in kilograms; a book title; whether a permission form is in.
2. Predict the output.

   rows = 8
   rows = rows + 4
   print(rows)

3. Predict the output. Explain the quotation marks.

   print(type("14"))

4. Find the fault. The club advisor types 6.5 and this crashes.

   answer = input("Kilograms collected: ")
   total = answer + 2.5

5. Predict the output.

   minutes = 185
   print(f"{minutes / 60:.1f}")

6. Rename these so the next reader does not have to guess: x = 12, n = "Priya", flag = True.
7. Write a program that asks for a name and a number of days, then prints Priya, the trip is in 14 days.
8. Challenge. A coach has total_minutes = 250. Print it as 4 h 10 min, without using a decimal point anywhere.

Answers

Answer 1

int for chairs (you count them, and half a chair is not a thing), float for kilograms (measurements have decimals), str for a title, bool for whether the form is in. If you were tempted by str for the mass, remember that text cannot be added up.

Answer 2

12. The second line is not a contradiction — = means “work out the right-hand side and store it in the name on the left”. Python computes 8 + 4 first, then puts 12 back into rows.

Answer 3

<class 'str'>. The quotation marks make it text, not a number. "14" and 14 look identical when printed and behave completely differently: one can be added to 1 and one cannot.

Answer 4

input() always returns text, so answer is the string "6.5", and Python refuses to add a number to text:

TypeError: can only concatenate str (not "float") to str

Convert first, on its own line:

answer = input("Kilograms collected: ")
kilograms = float(answer)
total = kilograms + 2.5

float, not int — int("6.5") raises ValueError, because int only accepts text that spells a whole number.

Answer 5

3.1. The division gives 3.0833333333333335; :.1f rounds the display to one decimal place. The value stored is unchanged — formatting is about the reader, not the arithmetic.

Answer 6

Something like chairs_per_row = 12, player_name = "Priya", form_returned = True. Boolean names read best as a claim that is either true or false, so form_returned beats flag and beats is_form too.

Answer 7

name = input("Name: ")
days = int(input("Days until the trip: "))
print(f"{name}, the trip is in {days} days.")

Name: Priya
Days until the trip: 14
Priya, the trip is in 14 days.

The int() is not strictly needed to print the number — but the moment anybody wants to subtract from it, text will not do.

Answer 8

total_minutes = 250
print(f"{total_minutes // 60} h {total_minutes % 60} min")

4 h 10 min

// divides and discards the remainder; % keeps only the remainder. Ordinary / would give 4.1666... hours, which is a different and less useful sentence.