Why algorithms are step-by-step solutions in Intro to Computing - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to show the first step in an algorithm to add two numbers.

Intro to Computing

result = num1 [1] num2

Drag options to blanks, or click blank then click option'

A-

B+

C*

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using '-' instead of '+' will subtract instead of add.

The plus sign (+) is used to add two numbers step-by-step.

2fill in blank

medium

Complete the code to show the next step: checking if the result is greater than 10.

Intro to Computing

if result [1] 10:
    print('Result is large')

Drag options to blanks, or click blank then click option'

A>

B<

C==

D<=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' will check if result is less than 10, which is not what we want here.

The '>' symbol checks if the result is greater than 10, which is a step in decision-making.

3fill in blank

hard

Fix the error in the step that repeats printing numbers from 1 to 5.

Intro to Computing

for i in [1](1, 6):
    print(i)

Drag options to blanks, or click blank then click option'

Alist

Bloop

Carray

Drange

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'list' or 'array' will cause errors because they don't generate sequences like 'range'.

The 'range' function generates numbers from 1 to 5 step-by-step, which is needed for the loop.

4fill in blank

hard

Fill both blanks to create a step-by-step filter for even numbers in a list.

Intro to Computing

evens = [num for num in numbers if num [1] 2 == [2]]

Drag options to blanks, or click blank then click option'

A%

B0

C1

D//

Attempts:

3 left

💡 Hint

Common Mistakes

Using '//' instead of '%' will do floor division, not remainder.

The '%' operator finds the remainder, and '0' means the number is even if remainder is zero.

5fill in blank

hard

Fill both blanks to create a dictionary of word lengths for words longer than 3 letters.

Intro to Computing

lengths = {: {BLANK_2}} for [2] in words if len({{BLANK_3}}) > 3

Drag options to blanks, or click blank then click option'

Aword

Blen(word)

D{

Attempts:

3 left

💡 Hint

Common Mistakes

Not using curly braces will cause syntax errors.

The dictionary starts with '{', keys are words, values are their lengths using len(word).

Practice

1. What is the main reason algorithms are described as step-by-step solutions?

easy

A. They provide clear, ordered instructions to solve a problem.

B. They use complex math formulas to find answers.

C. They rely on guessing to get results quickly.

D. They only work for computer games.

Solution

1. Step 1: Understand the definition of an algorithm

   An algorithm is a set of clear, ordered steps designed to solve a problem.

2. Step 2: Identify why step-by-step is important

   Step-by-step instructions ensure the task is done in a logical order, avoiding confusion.

3. Final Answer:

   They provide clear, ordered instructions to solve a problem. -> Option A

4. Quick Check:

   Step-by-step = Clear instructions [OK]

Hint: Algorithms are like recipes with clear steps [OK]

Common Mistakes:

• Thinking algorithms guess answers
• Believing algorithms only apply to games
• Confusing algorithms with random processes

2. Which of the following shows the correct way to write an algorithm step?

easy

A. Start by mixing all ingredients together.

B. Mixing ingredients start all by.

C. Ingredients all mixing start by.

D. Start all ingredients mixing by.

Solution

1. Step 1: Check sentence clarity and order

   Start by mixing all ingredients together. has a clear, logical order describing the first step.

2. Step 2: Compare with other options

   Options A, C, and D have jumbled word order making them unclear.

3. Final Answer:

   Start by mixing all ingredients together. -> Option A

4. Quick Check:

   Clear order = Correct step [OK]

Hint: Algorithm steps must be clear and in order [OK]

Common Mistakes:

• Writing steps with mixed-up words
• Skipping important actions in steps
• Using vague instructions

3. Consider this simple algorithm to find the sum of two numbers:

Step 1: Take number A = 3
Step 2: Take number B = 5
Step 3: Add A and B
Step 4: Output the result

What will be the output?

medium

A. Error

B. 35

C. 15

D. 8

Solution

1. Step 1: Identify the input values

   Number A is 3 and number B is 5 as given.

2. Step 2: Perform the addition

   Adding 3 + 5 equals 8.

3. Final Answer:

   8 -> Option D

4. Quick Check:

   3 + 5 = 8 [OK]

Hint: Add numbers step-by-step as instructed [OK]

Common Mistakes:

• Concatenating numbers as strings (35)
• Multiplying instead of adding
• Assuming syntax error

4. An algorithm to find the largest of two numbers is:

Step 1: Input numbers X and Y
Step 2: If X > Y, print X
Step 3: If Y > X, print Y
Step 4: End

What is wrong with this algorithm if it prints nothing when X = Y?

medium

A. Step 4 is missing a print statement.

B. The comparison operator should be < instead of >.

C. It does not handle the case when X equals Y.

D. Input step is incorrect.

Solution

1. Step 1: Analyze the conditions

   The algorithm prints X if X is greater than Y, prints Y if Y is greater than X.

2. Step 2: Check what happens if X equals Y

   If X equals Y, neither condition triggers a print, so nothing is printed.

3. Final Answer:

   It does not handle the case when X equals Y. -> Option C

4. Quick Check:

   Missing equal case = No output [OK]

Hint: Check all possible cases including equals [OK]

Common Mistakes:

• Ignoring equal values in conditions
• Changing comparison operator incorrectly
• Assuming input step causes no output

5. You want to create an algorithm to prepare a cup of tea. Which of the following best shows why step-by-step instructions are important?

hard

A. Stirring tea after drinking improves flavor.

B. Skipping steps like boiling water can cause the tea to be cold.

C. Pouring tea before adding tea leaves saves time.

D. Adding sugar before boiling water makes the tea sweeter.

Solution

1. Step 1: Understand the tea-making process

   Boiling water is essential before adding tea leaves to make hot tea.

2. Step 2: Identify the effect of skipping steps

   If boiling water is skipped, tea will be cold and not properly brewed.

3. Final Answer:

   Skipping steps like boiling water can cause the tea to be cold. -> Option B

4. Quick Check:

   Step order affects result [OK]

Hint: Follow steps in order for correct results [OK]

Common Mistakes:

• Thinking order of steps does not matter
• Assuming adding sugar changes temperature
• Ignoring importance of boiling water