Chapter 4: Data and Variables

The answers on this page show ONE way to solve the exercises. However, there are usually OTHER ways to accomplish the same thing. This is OK!

A suggested solution is ONE way to solve the problem, not the ONLY way.

Chapter Sandbox

Use the editor below to test out any of the solutions!

Solutions

Part A

  1. Add parenthesis to the expression 6 * 1 - 2 to change its value from 4 to -6.

    print(6 * (1 - 2))

  1. Print a selected word in several different patterns.

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    word = 'Rutabaga'

# Part a: Print the word 4 times on the same line, with spaces in between.
print(word, word, word, word)

# Part b: Print 3 lines of 2 words each. Use a single print statement.
print(word*2 + '\n' + word*2 + '\n' + word*2)   # '\n' moves the output to a newline.

# Part c: Print 3 lines of 3 words each, with tabs between the words.
# There are a number of ways to solve this part!

# One way:
print(word + '\t' + word + '\t' + word)  # Single line of 3 words (with tabs).
print(word + '\t' + word + '\t' + word)  # Second line
print(word + '\t' + word + '\t' + word)  # Third line

# Another way:

print(((word+'\t')*3+'\n')*3)  # This way includes extra tabs and newline.

# Your way...

Back to the exercises.

Part B

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# 1. Declare and assign four variables:
ship_name = 'Determination'
speed_mph = 17500
km_to_mars = 225000000
mi_per_km = 0.621

# 2. Define and assign a miles to Mars variable:
miles_to_mars = km_to_mars * mi_per_km

# 3 & 4. Calculate and store the hours and days it takes to get to Mars:
hours_to_mars = miles_to_mars/speed_mph
days_to_mars = hours_to_mars/24

# 5. Print the sentence, "___ will take ___ days to reach Mars."
print(ship_name, 'will take', days_to_mars, 'days to reach Mars.')

# 6. Bonus mission:
km_to_moon = 384400                     # Assign distance value (in km).
mi_to_moon = km_to_moon * 0.621         # Convert km to miles.
hours_to_moon = mi_to_moon/speed_mph    # Calculate hours to moon.
days_to_moon = hours_to_moon/24         # Calculate days to moon.
print(ship_name, 'will take', days_to_moon, 'days to reach the Moon.')

Back to the exercises.

Part C

  1. After the user enters a word, print the message, The word '___' contains ___ characters.

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    user_word = input('Please enter a word: ')
num_chars = len(user_word)
print("The word '" + user_word + "' contains", num_chars, "characters." )

  1. Write a program that will find the miles per gallon for a car.

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    miles_driven = float(input('How many miles did you drive? '))
gallons_used = float(input('How many gallons did you use? '))
print('Your car got', miles_driven/gallons_used, 'miles per gallon.')

Note

In Part C, questions 2 & 3, we use int() and float() to convert a string value into a numerical data type.

What happens if a user enters a decimal value (like 3.33) for an int() input? What if they enter a whole number for a float() input? What happens if they enter letters instead? TRY IT!

Later, we will learn how to protect our programs against unexpected input values.

Back to the exercises.