Day 3 - Data

A programmer is writing a program that is intended to be able to process large amounts of data. Which of the following considerations is LEAST likely to affect the ability of the program to process larger data sets?

• How long the program takes to run

• How many programming statements the program contains

• How much memory the program requires as it runs

• How much storage space the program requires as it runs

A certain programming language uses 4-bit binary sequences to represent nonnegative integers. For example, the binary sequence 0101 represents the corresponding decimal value 5. Using this programming language, a programmer attempts to add the decimal values 14 and 15 and assign the sum to the variable total. Which of the following best describes the result of this operation?

• The correct sum of 29 will be assigned to the variable total.

• An overflow error will occur because 4 bits is not large enough to represent either of the values 14 or 15.

• An overflow error will occur because 4 bits is not large enough to represent 29, the sum of 14 and 15.

• A round-off error will occur because the decimal values 14 and 15 are represented as approximations due to the fixed number of bits used to represent numbers.

A researcher is analyzing data about students in a school district to determine whether there is a relationship

between grade point average and number of absences. The researcher plans on compiling data from several

sources to create a record for each student.

The researcher has access to a database with the following information about each student.

• Last name

• First name

• Grade level (9, 10, 11, or 12)

• Grade point average (on a 0.0 to 4.0 scale)

The researcher also has access to another database with the following information about each student.

• First name

• Last name

• Number of absences from school

• Number of late arrivals to school

Upon compiling the data, the researcher identifies a problem due to the fact that neither data source uses a

unique ID number for each student. Which of the following best describes the problem caused by the lack of

unique ID numbers?

• Students who have the same name may be confused with each other.

• Students who have the same grade point average may be confused with each other.

• Students who have the same grade level may be confused with each other.

• Students who have the same number of absences may be confused with each other.

A video-streaming Web site keeps count of the number of times each video has been played since it was

first added to the site. The count is updated each time a video is played and is displayed next to each video

to show its popularity.

At one time, the count for the most popular video was about two million. Sometime later, the same video

displayed a seven-digit negative number as its count, while the counts for the other videos displayed

correctly. Which of the following is the most likely explanation for the error?

• The count for the video became larger than the maximum value allowed by the data type used to store the count.

• The mathematical operations used to calculate the count caused a rounding error to occur.

• The software used to update the count failed when too many videos were played simultaneously by too many users.

• The software used to update the count contained a sampling error when using digital data to approximate the analog count.

In a certain computer program, two positive integers are added together, resulting in an overflow error.

Which of the following best explains why the error occurs?

• The program attempted to perform an operation that is considered an undecidable problem.

• The precision of the result is limited due to the constraints of using a floating-point representation.

• The program can only use a fixed number of bits to represent integers; the computed sum is greater than the maximum representable value.

• The program cannot represent integers; the integers are converted into decimal approximations, leading to rounding errors.

Which of the following CANNOT be determined using only the information in the database?

• The date when a certain movie was purchased the greatest number of times

• The number of movies purchased by an individual subscriber for a particular month

• The total number of cities in which a certain movie was purchased

• The total number of movies purchased in a certain city during a particular month

An employee wants to count the number of books that meet all of the following criteria.

• Is a mystery book

• Costs less than $10.00

• Has at least one copy in stock

For a given row in the spreadsheet, suppose genre contains the genre as a string, num contains the number of copies in stock as a number, and cost contains the cost as a number. Which of the following expressions will evaluate to true if the book should be counted and evaluates to false otherwise?

• (genre = "mystery")

  AND

  ((1 ≤ num) AND (cost < 10.00))

• (genre = "mystery")

  AND

  ((1 < num) AND (cost < 10.00))

• (genre = "mystery")

  OR

  ((1 ≤ num) OR (cost < 10.00))

• (genre = "mystery")

  OR

  ((1 < num) OR (cost < 10.00))

A store employee wants to calculate the total amount of money the store will receive if they sell all of the available science fiction books. Which columns in the

database can be ignored and still allow the employee to perform this calculation?

Select two answers.

• Author

• Title

• Genre

• Quantity Available

A video game character can face toward one of four directions: north, south, east, and west. Each direction

is stored in memory as a sequence of four bits. A new version of the game is created in which the character

can face toward one of eight directions, adding northwest, northeast, southwest, and southeast to the original

four possibilities. Which of the following statements is true about how the eight directions must be stored in

memory?

• Four bits are not enough to store the eight directions. Five bits are needed for the new version of the game.

• Four bits are not enough to store the eight directions. Eight bits are needed for the new version of the game.

• Four bits are not enough to store the eight directions. Sixteen bits are needed for the new version of the game.

• Four bits are enough to store the eight directions.

An online store uses 6-bit binary sequences to identify each unique item for sale. The store plans to increase the number of items it sells and is considering using 7-bit binary sequences. Which of the following best describes the result of using 7-bit sequences instead of 6-bit sequences?

• 2 more items can be uniquely identified.

• 10 more items can be uniquely identified.

• 2 times as many items can be uniquely identified.

• 10 times as many items can be uniquely identified.