📝 3.3 Homework: Math Expressions & Algorithms in Python

Learning Objectives

  1. Write a Python program that follows a step-by-step algorithm.
  2. Use sequencing correctly in Python.
  3. Use arithmetic operators and variables to calculate results.

Part 1: Sequencing & Variables

Write a Python program that performs the following steps in order:

  1. Create a variable grade1 and assign it a value of 90.
  2. Create a variable grade2 and assign it a value of 75.
  3. Calculate the average of grade1 and grade2 and store it in a variable called averageGrade.
  4. Display the value of averageGrade.

Example Output:
The average grade is 82.5

grade1 = 90
grade2 = 75

averageGrade = (grade1 + grade2) / 2

print("The average grade is", averageGrade)

Part 2: Arithmetic Expressions

Calculate the following in Python using variables and arithmetic operators:

  1. num1 ← 10
  2. num2 ← 5
  3. num3 ← num1 + num2 * 2
  4. num4 ← (num1 + num2) * 2
  5. num5 ← num3 / 3 + num4
  6. Display the values of num3, num4, and num5.

Hint: Use +, -, *, /, and parentheses to control order of operations.

num1 = 10
num2 = 5

num3 = num1 + num2 * 2    
num4 = (num1 + num2) * 2 
num5 = num3 / 3 + num4

print("num3 =", num3)
print("num4 =", num4)
print("num5 =", num5)

Part 3: Step-by-Step Algorithm Practice

Write Python code for this algorithm without using loops or if statements:

Algorithm:

  1. Set item to 7
  2. Create three variables: num1 = 3, num2 = 7, num3 = 9
  3. Check each variable manually to see if it equals item (just write it as a sequence of assignments and displays)
  4. Display "Item found" if a variable matches item
  5. At the end, display "Item not found" if none match

Hint: Since you haven’t learned if statements, just write a sequence that shows the comparisons step by step with comments.

item = 7
num1 = 3
num2 = 7
num3 = 9

print("Checking num1:", num1 == item) 
print("Checking num2:", num2 == item) 
print("Checking num3:", num3 == item) 

print("Item found")   
print("Item not found")

Part 4: Mixed Expressions

Write a Python program that:

  1. Create three variables: a = 8, b = 4, c = 10
  2. Calculate:
    • result1 = a + b * c
    • result2 = (a + b) * c
    • result3 = a + (b / c)
  3. Display all three results.

This will help you practice order of operations and arithmetic in Python.

a = 8
b = 4
c = 10

result1 = a + b * c
result2 = (a + b) * c
result3 = a + (b / c)

print("Result 1:", result1)
print("Result 2:", result2)
print("Result 3:", result3)