Unit 5 code.org Review

What is displayed as a result of executing the code segment?

• 1 3 5

• 5 3 1

• 100 300 500

• 500 300 100

Shoppers at a mall were asked whether they preferred wearing gloves or mittens in cold weather. Shoppers’ preferences were stored in the list voteList as strings, with the string "Gloves" representing a preference for gloves and the string "Mittens" representing a preference for mittens.

The following code segment is intended to traverse the list and display the number of shoppers who chose gloves and the number of shoppers who chose mittens.

numGlovesVotes ←0

numMittensVotes ← 0

<MISSING CODE>

{

IF(vote = "Gloves")

{

numGlovesVotes ← numGlovesVotes + 1

}

ELSE

{

numMittensVotes ← numMittensVotes + 1

}

}

DISPLAY(numGlovesVotes)

DISPLAY(" shoppers chose gloves and")

DISPLAY(numMittensVotes)

DISPLAY(" shoppers chose mittens.")

Which of the following should replace <MISSING CODE> so that the code segment works as intended?

• IF(vote ≤ LENGTH(voteList))

• FOR EACH vote IN voteList

• REPEAT LENGTH(voteList) TIMES

• REPEAT UNTIL(vote > LENGTH(voteList))

Consider the following code segment. Assume that index1 is a number between 1 and LENGTH(theList), inclusive, and index2 is a number between 2 and LENGTH(theList) - 1, inclusive.

theList ← [9, -1, 5, 2, 4, 8]

x ← theList[index1] + theList[index2]

What is the largest possible value that the variable x can have after the code segment executes?

• 17

• 14

• 11

• 4

Consider the following code segment, which is intended to store ten consecutive even integers, beginning with 2, in the list evenList. Assume that evenList is initially empty.

i ← 1

REPEAT 10 TIMES

{

<MISSING CODE>

}

Which of the following can be used to replace <MISSING CODE> so that the code segment works as intended?

• APPEND(evenList, i)

  i ← i + 2

• i ← i + 2

  APPEND(evenList, i)

• APPEND(evenList, 2 * i)

  i ← i + 1

• i ← i + 1

  APPEND(evenList, 2 * i)

A teacher stores the most recent quiz scores for her class in the list scores. The first element in the list holds the maximum possible number of points that can be awarded on the quiz, and each remaining element holds one student’s quiz score. Assume that scores contains at least two elements. Which of the following code segments will set the variable found to true if at least one student scored the maximum possible number of points on the quiz and will set found to false otherwise?

• 
• 
• 
• 

Consider the following code segment.

theList ← [-2, -1, 0, 1, 2]

count1 ← 0

count2 ← 0

FOR EACH value IN theList

{

IF(value > 0)

{

count1 ← count1 + 1

}

ELSE

{

count2 ← count2 + 1

}

}

What are the values of count1 and count2 as a result of executing the code segment?

• count1 = 2, count2 = 2

• count1 = 2, count2 = 3

• count1 = 3, count2 = 2

• count1 = 5, count2 = 0

Assume that both lists and strings are indexed starting with index 1.

The list wordList has the following contents.

["abc", "def", "ghi", "jkl"]

Let myWord be the element at index 3 of wordList. Let myChar be the character at index 2 of myWord. What is the value of myChar ?

• "e"

• "f"

• "h"

• "i"

A program contains the following procedures for string manipulation.

ExplanationConcat (str1, str2)Returns a single string consisting of str1 followed by str2. For example, Concat ("key", "board") returns "keyboard".

Substring (str, start, length)Returns a substring of consecutive characters from str, starting with the character at position start and containing length characters. The first character of str is located at position 1. For example, Substring ("delivery", 3, 4) returns "live".

Which of the following can be used to store the string "jackalope" in the string variable animal ?

• animal ←← Substring ("antelope", 5, 4)

  animal ←← Concat (animal, "a")

  animal ←← Concat (Substring ("jackrabbit", 1, 4), animal)

• animal ←← Substring ("antelope", 5, 4)

  animal ←← Concat ("a", animal)

  animal ←← Concat (Substring ("jackrabbit", 1, 4), animal)

• animal ←← Substring ("jackrabbit", 1, 4)

  animal ←← Concat (animal, "a")

  animal ←← Concat (animal, Substring ("antelope", 5, 4))

• animal ←← Substring ("jackrabbit", 1, 4)

  animal ←← Concat (animal, "a")

  animal ←← Concat (Substring ("antelope", 5, 4), animal)

Answer explanation

B. This code segment stores the substring "lope" in animal. It then concatenates "a" and "lope", storing the result "alope" in animal. Lastly, it concatenates the substring "jack" and "alope", storing the result "jackalope" in animal.

C. This code segment stores the substring "jack" in animal. It then concatenates "jack" and "a", storing the result "jacka" in animal. Lastly, it concatenates "jacka" and the substring "lope", storing the result "jackalope" in animal.

The following algorithm is intended to determine the average height, in centimeters, of a group of people in a room. Each person has a card, a pencil, and an eraser. Step 2 of the algorithm is missing.

Step 1: All people stand up.

Step 2: (missing step)

Step 3: Each standing person finds another standing person and they form a pair. If a person cannot find an unpaired standing person, that person remains standing and waits until the next opportunity to form pairs.

Step 4: In each pair, one person hands their card to the other person and sits down.

Step 5: At this point, the standing person in each pair is holding two cards. The standing person in each pair replaces the top number on their card with the sum of the top numbers on the two cards and replaces the bottom number on their card with the sum of the bottom numbers on the two cards. The sitting partner’s card is discarded.

Step 6: Repeat steps 3–5 until there is only one person standing.

Step 7: The last person standing divides the top number by the bottom number to determine the average height.

Which of the following can be used as step 2 so that the algorithm works as intended?

• Step 2: Each person writes their height, in centimeters, at the top of the card and writes the number 1 at the bottom of the card.

• Step 2: Each person writes their height, in centimeters, at the top of the card and writes the number 2 at the bottom of the card.

• Step 2: Each person writes the number 1 at the top of the card and writes their height, in centimeters, at the bottom of the card.

• Step 2: Each person writes the number 2 at the top of the card and writes their height, in centimeters, at the bottom of the card.

Answer explanation

By starting the process by writing a height at the top of the card and writing a 1 at the bottom of the card, the algorithm will work such that the last person’s card will have the sum of the heights at the top and the number of people at the bottom. The sum of the heights divided by the number of people gives the average height.

Consider the following program.

Which of the following describes the result of executing the program?

• The program displays the sum of the even integers from 2 to 10.

• The program displays the sum of the even integers from 2 to 20.

• The program displays the sum of the odd integers from 1 to 9.

• The program displays the sum of the odd integers from 1 to 19.

Answer explanation

The value of val starts at 0 and is repeatedly incremented by 2, so the program calculates the sum of even integers. Inside the loop, val is incremented by 2 before being added to sum, so the first value added to sum is 2. The loop iterates 10 times, adding each intermediate value of val each time. Therefore, the program displays the sum of the even integers starting at 2 and ending at 20.