Big Idea 2: Data Questions

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.

Which of the following is an advantage of a lossless compression algorithm over a lossy compression algorithm?

• A lossless compression algorithm can guarantee that compressed information is kept secure, while a lossy compression algorithm cannot.

• A lossless compression algorithm can guarantee reconstruction of original data, while a lossy compression algorithm cannot.

• A lossless compression algorithm typically allows for faster transmission speeds than does a lossy compression algorithm.

• A lossless compression algorithm typically provides a greater reduction in the number of bits stored or transmitted than does a lossy compression algorithm.

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.

A large spreadsheet contains the following information about the books at a bookstore. A sample portion of the spreadsheet is shown.

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 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 team of researchers wants to create a program to analyze the amount of pollution reported in roughly 3,000 counties across the United States. The program is intended to combine county data sets and then process the data. Which of the following is most likely to be a challenge in creating the program?

• A computer program cannot combine data from different files.

• Different counties may organize data in different ways.

• The number of counties is too large for the program to process.

• The total number of rows of data is too large for the program to process.

A student is creating a Web site that is intended to display information about a city based on a city name that a user enters in a text field. Which of the following are likely to be challenges associated with processing city names that users might provide as input?

Select two answers.

• Users might attempt to use the Web site to search for multiple cities.

• Users might enter abbreviations for the names of cities.

• Users might misspell the name of the city.

• Users might be slow at typing a city name in the text field.

The owner of a clothing store records the following information for each transaction made at the store during a 7-day period.

> The date of the transaction

> The method of payment used in the transaction

> The number of items purchased in the transaction

> The total amount of the transaction, in dollars

Customers can pay for purchases using cash, check, a debit card, or a credit card.

Using only the data collected during the 7-day period, which of the following statements is true?

• The average amount spent per day during the 7-day period can be determined by sorting the data by the total transaction amount, then adding the 7 greatest amounts, and then dividing the sum by 7.

• The method of payment that was used in the greatest number of transactions during the 7-day period can be determined by sorting the data by the method of payment, then adding the number of items purchased for each type of payment method, and then finding the maximum sum.

• The most expensive item purchased on a given date can be determined by searching the data for all items purchased on the given date and then sorting the matching items by item price.

• The total number of items purchased on a given date can be determined by searching the data for all transactions that occurred on the given date and then adding the number of items purchased for each matching transaction.

A user wants to save a data file on an online storage site. The user wants to reduce the size of the file, if possible, and wants to be able to completely restore the file to its original version. Which of the following actions best supports the user’s needs?

• Compressing the file using a lossless compression algorithm before uploading it

• Compressing the file using a lossy compression algorithm before uploading it

• Compressing the file using both lossy and lossless compression algorithms before uploading it

• Uploading the original file without using any compression algorithm

A company uses the pictured data files. A new rechargeable battery pack is available for products that use AA batteries. Which of the following best explains how the data files in the table can be used to send a targeted e-mail to only those customers who have purchased products that use AA batteries to let them know about the new accessory?

• Use the customer IDs in the purchases file to search the customers file to generate a list of e-mail addresses

• Use the product IDs in the purchases file to search the products file to generate a list of product names that use AA batteries

• Use the customers file to generate a list of customer IDs, then use the list of customer IDs to search the products file to generate a list of product names that use AA batteries

• Use the products file to generate a list of product IDs that use AA batteries, then use the list of product IDs to search the purchases file to generate a list of customer IDs, then use the list of customer IDs to search the customers file to generate a list of e-mail addresses