khan academy programming unit test
A digital artist is creating an animation with code. Their code needs to convert polar coordinates to
cartesian coordinates, using these formulas:
x = r × cos( θ )\\y = r × sin( θ )x=r×cos(θ)y=r×sin(θ)
The environment provides these built-in procedures:
NameDescriptionsin(angle)Returns the sine of the given angle.cos(angle)Returns the cosine of the given
angle.
In their code, theta represents the current angle and r represents the current radius.
Which of these code snippets properly implements the conversion formulas? correct answerx ← r *
cos(theta)
y ← r * sin(theta)
Yong is making a program to help him figure out how much money he spends eating.
This procedure calculates a yearly cost based on how much an item costs, and how many times a week
he consumes it:
PROCEDURE calcYearlyCost(numPerWeek, itemCost) { numPerYear ← numPerWeek * 52 yearlyCost ←
numPerYear * itemCost RETURN yearlyCost }
Yong wants to use that procedure to calculate the total cost of his breakfast beverages:
hot tea, which he drinks 5 days a week and costs $2.00
boba, which he drinks 2 days a week and costs $6.00
Which of these code snippets successfully calculates and stores their total cost?
👁️Note that there are 2 answers to this question. correct answertotalCost ← calcYearlyCost(2, 6.00) +
calcYearlyCost(5, 2.00)
teaCost ← calcYearlyCost(5, 2.00) bobaCost ← calcYearlyCost(2, 6.00) totalCost ← teaCost + bobaCost
The following code snippet processes a list of strings with a loop and conditionals:
words ← ["belly", "rub", "kitty", "pet", "cat", "water"] counter ← 0 FOR EACH word IN words { IF
(FIND(word, "e") = -1 AND FIND(word, "a") = -1) { counter ← counter + 1 } } DISPLAY(counter)
,The code relies on one string procedure, FIND(source, target), which returns the first index of the string
target inside of the string source, and returns -1 if target is not found.
What value will this program display? correct answer2
Lucie is developing a program to assign pass/fail grades to students in her class, based on their
percentage grades.
Their college follows this grading system:
PercentageGrade70% and abovePASSLower than 70%FAIL
The variable percentGrade represents a student's percentage grade, and her program needs to set grade
to the appropriate value.
Which of these code segments correctly sets the value of grade?
👁️Note that there are 2 answers to this question. correct answerIF (percentGrade ≥ 70) { grade ←
"PASS" } ELSE { grade ← "FAIL" }
IF (percentGrade < 70) { grade ← "FAIL" } ELSE { grade ← "PASS" }
The following numbers are displayed by a program:
4556
The program code is shown below, but it is missing three values: <COUNTER>, <AMOUNT>, and <STEP>.
i ← <COUNTER> REPEAT <AMOUNT> TIMES { DISPLAY(i) DISPLAY(i + 1) i ← i + <STEP> }
Given the displayed output, what must the missing values be? correct answer<COUNTER> = 4,
<AMOUNT> = 2, <STEP> = 1
This program uses a conditional to predict the hair type of a baby.
IF (fatherAllele = "C" AND motherAllele = "C") { hairType ← "curly" } ELSE { IF (fatherAllele = "s" AND
motherAllele = "s") { hairType ← "straight" } ELSE { hairType ← "wavy" } }
In which situations will hairType be "wavy"?
👁️Note that there may be multiple answers to this question. correct answerWhen fatherAllele is "s" and
motherAllele is "C"
When fatherAllele is "C" and motherAllele is "s"
,Darrell is making a program to track his grades. He made the mistake of using the same variable name to
track 3 different test grades, though. Here's a snippet of his code:
a ← 89 a ← 97 a ← 93
What will be the value of a after this code runs? correct answer93
The following procedure calculates the slope of a line and takes 4 numeric parameters: the x coordinate
of the first point, the y coordinate of the first point, the x coordinate of the second point, and the y
coordinate of the second point.
PROCEDURE lineSlope (x1, y1, x2, y2) { result ← (y2 - y1) / (x2 - x1) DISPLAY (result) }
This graph contains a line with unknown slope, going through the points [1, 1][1,1]open bracket, 1,
comma, 1, close bracket and [3, 4][3,4]open bracket, 3, comma, 4, close bracket:
\small{1}1\small{2}2\small{3}3\small{4}4\small{1}1\small{2}2\small{3}3\small{4}4yyxx
Graph with line going through 2 marked points [1, 1] and [3, 4]
Which of these lines of code correctly calls the procedure to calculate the slope of this line? correct
answerlineSlope(1, 1, 3, 4)
A local search website lets users create lists of their favorite restaurants.
When the user first starts, the website runs this code to create an empty list:
localFavs ← []
The user can then insert and remove items from the list.
Here's the code that was executed from one user's list making session:
APPEND(localFavs, "Udupi") APPEND(localFavs, "The Flying Falafel") APPEND(localFavs, "Rojbas Grill")
APPEND(localFavs, "Cha-Ya") APPEND(localFavs, "Platano") APPEND(localFavs, "Cafe Nostos")
INSERT(localFavs, 3, "Gaumenkitzel") REMOVE(localFavs, 5)
What does the localFavs variable store after that code runs? correct answer"Udupi", "The Flying Falafel",
"Gaumenkitzel", "Rojbas Grill", "Platano", "Cafe Nostos"
Aden is working on a program that can generate domain names.
His program uses the following procedure for string concatenation:
PseudocodeDescriptionconcatenate(string1, string2)Concatenates (joins) two strings to each other,
returning the combined string.
, These variables are at the start of his program:
company ← "cactus" tld1 ← "com" tld2 ← "io"
Which line of code would store the string "cactus.io"? correct answername2 ← concatenate(company,
concatenate(".", tld2))
This program simulates a game where two players try to make basketball shots . Once either player
misses 5 shots, the game is over.
1: player1Misses ← 0 2: player2Misses ← 0 3: REPEAT UNTIL (player1Misses = 5 OR player2Misses = 5) 4:
{ 5: player1Shot ← RANDOM(1, 2) 6: player2Shot ← RANDOM(1, 2) 7: IF (player1Shot = 2) 8: { 9:
DISPLAY("Player 1 missed! ☹") 10: } 11: IF (player2Shot = 2) 12: { 13: DISPLAY("Player 2 missed! ☹")
14: } 15: IF (player1Shot = 1 AND player2Shot = 1) 16: { 17: DISPLAY("No misses! ☺") 18: } 19: }
Unfortunately, this code is incorrect; the REPEAT UNTIL loop never stops repeating.
Where would you add code so that the game ends when expected?
👁️Note that there are 2 answers to this question. correct answerBetween line 9 and 10
Between line 13 and 14
This short program displays the winning result in the Greenpeace whale naming contest:
DISPLAY ("Mister") DISPLAY ("Splashy") DISPLAY ("Pants")
Part 1: How many statements are in the above program?
Part 2: What does the program output? correct answer3
Mister Splashy Pants
Nanami is researching how much software engineers make. She's writing a program to convert yearly
salaries into hourly rates, based on 52 weeks in a year and 40 hours in a week.
The program starts with this code:
salary ← 105000 wksInYear ← 52 hrsInWeek ← 40
Which lines of code successfully calculate and store the hourly rate?
