APCSP Data Representation 3 — Questions and Answers
Question 1: An analog signal differs from a digital signal in that an analog signal:
- can only take on two discrete values
- varies continuously over a range of values (Correct answer)
- is immune to noise and interference
- is always represented in binary
Correct answer: varies continuously over a range of values
Analog signals vary continuously and can take on any value within a range, whereas digital signals represent data as discrete values.
Question 2: When converting an analog audio recording to digital, increasing the sampling rate primarily improves:
- the dynamic range of quiet vs. loud sounds
- the accuracy of representing high-frequency sounds (Correct answer)
- the number of bits used per sample
- the file compression ratio
Correct answer: the accuracy of representing high-frequency sounds
A higher sampling rate captures more detail per second, allowing higher-frequency audio components to be accurately represented.
Question 3: Which of the following is an example of metadata?
- The pixel colors that make up a photograph
- The date, location, and camera settings stored alongside a JPEG image (Correct answer)
- The text body of an email message
- The audio waveform in an MP3 file
Correct answer: The date, location, and camera settings stored alongside a JPEG image
Metadata is data about data; EXIF information like date taken and GPS coordinates describes the image without being part of the visual content itself.
Question 4: What does the term 'bit depth' refer to in the context of digital audio?
- The number of audio channels (mono, stereo, etc.)
- The number of bits used to represent each audio sample, affecting dynamic range (Correct answer)
- The frequency at which samples are taken per second
- The compression algorithm applied to reduce file size
Correct answer: The number of bits used to represent each audio sample, affecting dynamic range
Bit depth determines how many distinct amplitude levels each sample can have; more bits means greater dynamic range and finer volume gradations.
Question 5: The binary number 11111111 equals which decimal value?
- 128
- 254
- 255 (Correct answer)
- 256
Correct answer: 255
All 8 bits set to 1: 128+64+32+16+8+4+2+1 = 255, which equals 2^8 − 1.
Question 6: In a spreadsheet, a cell stores the number 3.14159 and another cell stores the text '3.14159'. Which statement is true?
- Both cells store identical binary patterns
- The numeric cell can be used in calculations; the text cell cannot without conversion (Correct answer)
- The text cell uses less memory than the numeric cell
- Both representations are identical to the computer
Correct answer: The numeric cell can be used in calculations; the text cell cannot without conversion
Computers use different internal representations for numbers and text, so a text string that looks like a number cannot be used directly in arithmetic operations.
Question 7: Which statement about overflow errors in integer representation is correct?
- Overflow errors occur when a number is stored with too many decimal places
- Overflow occurs when a calculated value exceeds the maximum value the bit-width can store (Correct answer)
- Overflow only happens with floating-point numbers, not integers
- Overflow causes the computer to automatically switch to a larger data type
Correct answer: Overflow occurs when a calculated value exceeds the maximum value the bit-width can store
Integer overflow occurs when arithmetic produces a result outside the range representable by the fixed number of bits, often wrapping around to an incorrect value.
APCSP Data Representation 3
An analog signal differs from a digital signal in that an analog signal: