Logical operators in conditions in Python - Mini Project: Build & Apply

Using Logical Operators in Conditions

📖 Scenario: You are creating a simple program to check if a person is eligible for a special discount based on their age and membership status.

🎯 Goal: Build a program that uses logical operators and and or in conditions to decide if a person gets a discount.

📋 What You'll Learn

Create a dictionary with exact keys and values for a person's details

Create a variable to hold the minimum age for discount

Use a condition with and and or to check eligibility

Print the exact output message based on eligibility

💡 Why This Matters

🌍 Real World

Logical operators help computers make decisions based on multiple rules, like checking if someone qualifies for a discount or access.

💼 Career

Understanding logical conditions is essential for programming tasks in software development, data validation, and automation.

1

Create the person's data

Create a dictionary called person with these exact entries: 'name': 'Emma', 'age': 22, and 'member': True.

Python

# Create the dictionary called person with name, age, and member status
# Your code here

Hint

Use curly braces {} to create the dictionary and separate each key-value pair with commas.

2

Set the minimum age for discount

Create a variable called min_age and set it to 18.

Python

person = {'name': 'Emma', 'age': 22, 'member': True}
# Create the variable min_age and set it to 18
# Your code here

Hint

Just write min_age = 18 on a new line.

3

Check discount eligibility using logical operators

Create a variable called eligible that is True if the person's age is greater than or equal to min_age and the person is a member, or if the person's name is exactly 'Emma'. Use the logical operators and and or in the condition.

Python

person = {'name': 'Emma', 'age': 22, 'member': True}
min_age = 18
# Create the variable eligible using logical operators and conditions
# Your code here

Hint

Use parentheses to group conditions and combine them with and and or.

4

Print the eligibility result

Write a print statement that outputs exactly: "Emma is eligible for discount: True" using the person['name'] and eligible variables with an f-string.

Python

person = {'name': 'Emma', 'age': 22, 'member': True}
min_age = 18
eligible = (person['age'] >= min_age and person['member']) or (person['name'] == 'Emma')
# Print the eligibility result using an f-string
# Your code here

Hint

Use print(f"{person['name']} is eligible for discount: {eligible}") to show the result.

Practice

1. Which logical operator in Python means all conditions must be true for the whole expression to be true?

easy

A. xor

B. and

C. not

D. or

Solution

1. Step 1: Understand the meaning of 'and'

   The and operator returns true only if both conditions are true.

2. Step 2: Compare with other operators

   or needs only one true condition, not reverses truth, and xor is not a Python keyword.

3. Final Answer:

   and -> Option B

4. Quick Check:

   All conditions true = and [OK]

Hint: Remember: 'and' means all must be true [OK]

Common Mistakes:

• Confusing 'and' with 'or'
• Thinking 'not' means all true
• Using 'xor' which is not a Python keyword

2. Which of the following is the correct syntax to check if variable x is NOT equal to 10 and variable y is greater than 5?

easy

A. if x != 10 and y > 5:

B. if x <> 10 and y > 5:

C. if x != 10 & y > 5:

D. if x != 10 or y > 5:

Solution

1. Step 1: Check the inequality operator

   != is the correct 'not equal' operator in Python; <> is invalid syntax.

2. Step 2: Check logical operator usage

   and correctly combines two conditions; & is a bitwise operator and or changes logic.

3. Final Answer:

   if x != 10 and y > 5: -> Option A

4. Quick Check:

   Correct inequality and 'and' syntax [OK]

Hint: Use '!=' for not equal and 'and' to combine conditions [OK]

Common Mistakes:

• Using '<>' instead of '!='
• Using '&' instead of 'and'
• Using 'or' when 'and' is needed

3. What will be the output of this code?

age = 20
has_id = False
if age >= 18 and has_id:
    print('Allowed')
else:
    print('Denied')

medium

A. SyntaxError

B. Allowed

C. Denied

D. No output

Solution

1. Step 1: Evaluate each condition

   age >= 18 is True since 20 >= 18, but has_id is False.

2. Step 2: Apply 'and' operator

   True and False is False, so the else block runs.

3. Final Answer:

   Denied -> Option C

4. Quick Check:

   True and False = False [OK]

Hint: Both conditions must be true for 'and' to print Allowed [OK]

Common Mistakes:

• Assuming one True is enough with 'and'
• Confusing 'and' with 'or'
• Ignoring boolean value of variables

4. Find the error in this code snippet:

if not x > 10 or y < 5
    print('Check passed')

medium

A. Missing colon ':' after condition

B. Wrong use of 'not' operator

C. Incorrect indentation

D. Using 'or' instead of 'and'

Solution

1. Step 1: Check syntax of if statement

   Python requires a colon ':' at the end of the if condition line.

2. Step 2: Review other parts

   The use of not and or is correct; indentation is not shown as wrong here.

3. Final Answer:

   Missing colon ':' after condition -> Option A

4. Quick Check:

   if statements need ':' [OK]

Hint: Always put ':' after if condition [OK]

Common Mistakes:

• Forgetting ':' after if
• Misusing 'not' operator
• Wrong indentation without colon

5. You want to check if a number n is either less than 0 or greater than 100, but NOT equal to -10. Which condition correctly uses logical operators?

hard

A. if n < 0 or (n > 100 and n != -10):

B. if n < 0 and n > 100 or n != -10:

C. if not (n < 0 or n > 100) and n == -10:

D. if (n < 0 or n > 100) and n != -10:

Solution

1. Step 1: Understand the condition requirements

   We want numbers less than 0 or greater than 100, but exclude -10.

2. Step 2: Analyze each option

   if (n < 0 or n > 100) and n != -10: correctly groups the or condition and excludes -10 with and n != -10. if n < 0 or (n > 100 and n != -10): excludes -10 only when >100, not <0 (e.g., n=-10 is true). if not (n < 0 or n > 100) and n == -10: reverses logic and checks for equal -10. if n < 0 and n > 100 or n != -10: mixes and/or incorrectly.

3. Final Answer:

   if (n < 0 or n > 100) and n != -10: -> Option D

4. Quick Check:

   Group or, then exclude -10 with and [OK]

Hint: Group or conditions, then exclude with and [OK]

Common Mistakes:

• Wrong grouping of conditions
• Misplacing 'not' or 'and'
• Confusing '!=' with '=='