Data Representation

ASCII is a character set. It uses 7 or 8 bits for one character. Unicode is another character set. It uses more bits. It can show many different languages and symbols. A developer wants to change a text file from ASCII to Unicode. Based on the information, what is a true effect of this change? (5 Point)

• Unicode uses more bits but the file size is smaller than an ASCII file.

• ASCII and Unicode use the same number of bits and have the same file size.

• Unicode uses fewer bits and can show fewer characters, so the file size is smaller.

• Unicode uses more bits and can show more characters, but the file size is bigger.

• ASCII uses more bits and can show more characters, but the file size is bigger.

A student has a very large bitmap image file in megabytes. The storage space is very small. The student wants to make the file size much smaller in kilobytes. They can change the bit-depth and the type of compression. A student wants to reduce a large image file for a small storage space: I. High bit-depth creates a very large file. II. Lossy compression removes some data to save space. III. Lossless compression keeps all data and saves less space. Which action is the most effective to reduce the file size? (5 Point)

• Use no compression and keep the original bit-depth of the image

• Use lossless compression and decrease the bit-depth of the image

• Use lossy compression and increase the bit-depth of the image

• Use lossy compression and decrease the bit-depth of the image

• Use lossless compression and increase the bit-depth of the image

Computers use binary numbers to show text. ASCII is an old system. It uses 8 bits for one character. Unicode is a new system. It can show characters from many languages. Unicode often uses 16 bits or more for one character. A student compares ASCII and Unicode for a text file in a multimedia project. Which statement is correct about these character sets? (5 Point)

• ASCII uses more bits than Unicode and it can show all the languages in the world.

• ASCII is better for multimedia because it shows images and Unicode only shows text.

• Unicode and ASCII use the same number of bits so the file size is always the same.

• Unicode makes the file size smaller because it uses very simple binary numbers for text.

• Unicode uses more bits for each character and makes the file size bigger than ASCII.

A programmer wants to save space on a computer. The data has many repeating bits in a row. The programmer needs to keep all the original data exactly as it is. This is called lossless compression. One common method for this is Run-Length Encoding (RLE). A programmer needs to make a data file smaller without losing any information. Which method is the best way to achieve this goal using Run-Length Encoding? (5 Point)

• Change the file format to a smaller size by removing some parts of the data

• Delete all small data values to save space in the binary file

• Convert the entire file into a single large number to use less storage

• Reduce the number of bits for every single value in the file

• Use Run-Length Encoding to store repeated data values as a single value and a count

Computer storage uses different labels for data sizes. A kibibyte (KiB) is 1,024 bytes, but a kilobyte (KB) is 1,000 bytes. This pattern continues for mebibytes (MiB) and megabytes (MB). Engineers must calculate these differences to show the correct space on a disk. A storage device has a capacity of exactly 8 MiB. What is this capacity when measured in decimal Megabytes (MB)? (5 Point)

• 8,192 MB

• 7.81 MB

• 8.00 MB

• 8,000 MB

• 8.39 MB

Digital systems use binary to store text. ASCII and Unicode are two ways to do this. ASCII is old and small. Unicode is new and very big. They use different numbers of bits for each letter. Read the following statements about character sets: I. Unicode uses more binary bits for one character than ASCII. II. Unicode can represent characters from many different languages. III. Changing text to Unicode always makes the binary file smaller. Which statements are true? (5 Point)

• II and III

• I and II

• Only I

• I, II, and III

• I and III

Computer users often use compression to make files smaller. There are two main types: lossy and lossless. Lossy compression removes some data to save a lot of space. Lossless compression keeps all the data but saves a little space. Different files need different types of compression. Consider the following statements about data compression: I. Lossy compression permanently removes some data to reduce the file size. II. Lossless compression allows the original file to be restored perfectly. III. Sound files always use lossless compression to keep the best quality. Which statements are correct? (5 Point)

• I and III

• II and III

• Only I

• Only III

• I and II

Data can be shown in different ways. Binary Coded Decimal (BCD) shows each denary digit with four bits. Hexadecimal uses sixteen symbols to show large binary numbers in a short way. Different systems are good for different tasks in a computer. The following statements are about number systems: I. BCD uses more bits than standard binary to store the number 1,000. II. In BCD, the binary pattern 1100 is not a valid digit. III. Hexadecimal is a base-12 system used to represent colors. Which statements are correct? (5 Point)

• I and III

• Only I

• II and III

• I and II

• Only III

A computer has 4 bits for numbers. It uses two's complement. Two numbers are 0111 and 0001. A student adds these numbers. The answer is 1000. A student looks at the result 1000 and thinks about these ideas: I. The result is 8 in denary. II. The result is -8 in two's complement. III. There is an overflow error because the sign changes. Which ideas are correct? (5 Point)

• Only I

• I and II

• Only III

• II and III

• I and III

When a computer uses lossy compression on a big image file, a person can later change it back to the exact original binary data. (1 Point)

• True

• False