Predicate methods (ending with ?) in Ruby - Mini Project: Build & Apply

Using Predicate Methods Ending with ? in Ruby

📖 Scenario: You are building a simple program to check properties of numbers in a list. You want to find out which numbers are even and which are odd using Ruby's predicate methods.

🎯 Goal: Create a Ruby program that uses predicate methods ending with ? to check if numbers are even or odd, and then prints the results.

📋 What You'll Learn

Create an array called numbers with the exact values: 2, 5, 8, 11, 14

Create a variable called threshold and set it to 10

Use a for loop with variable num to iterate over numbers and inside the loop use the predicate method even? to check if num is even

Inside the loop, also check if num is greater than threshold

Print the number and whether it is even and if it is greater than the threshold in the format: "2 is even and less than or equal to 10" or "11 is odd and greater than 10"

💡 Why This Matters

🌍 Real World

Checking conditions like even or odd numbers is common in programs that handle data filtering, validation, or decision making.

💼 Career

Understanding predicate methods helps you write clear and readable code, which is important for software development jobs that require condition checks and logic.

1

Create the numbers array

Create an array called numbers with these exact values: 2, 5, 8, 11, 14

Ruby

# Create an array called numbers with 2, 5, 8, 11, 14
# Your code here

Need a hint?

Use square brackets [] to create an array and separate numbers with commas.

2

Set the threshold variable

Create a variable called threshold and set it to 10

Ruby

numbers = [2, 5, 8, 11, 14]
# Create a variable called threshold and set it to 10
# Your code here

Need a hint?

Use = to assign the value 10 to the variable threshold.

3

Use a for loop and predicate methods

Use a for loop with variable num to iterate over numbers. Inside the loop, use the predicate method even? on num to check if it is even. Also check if num is greater than threshold.

Ruby

numbers = [2, 5, 8, 11, 14]
threshold = 10
# Use a for loop with num to iterate over numbers
# Inside the loop, use num.even? and compare num with threshold
# Your code here

Need a hint?

Use for num in numbers to loop. Use num.even? to check evenness and num > threshold to compare.

4

Print the results

Inside the for loop, print the number and whether it is even or odd, and if it is greater than the threshold or not. Use this exact format: "2 is even and less than or equal to 10" or "11 is odd and greater than 10"

Ruby

numbers = [2, 5, 8, 11, 14]
threshold = 10
for num in numbers
  is_even = num.even?
  is_greater = num > threshold
  # Print the result in the required format
  # Your code here
end

Need a hint?

Use puts with string interpolation and the ternary operator ? : to print the message.