Computer Science VERIFIED SOLUTIONS 2023/2024

Computer Science VERIFIED SOLUTIONS 2023/2024 What is a Natural Number and its Symbol? - ANSWER Positive Integer (N) What is a Real Number and its Symbol? - ANSWER Any number (R) What is an Integer and its Symbol? - ANSWER Any whole number (Z) What is a Rational Number and its Symbol? - ANSWER Can be represented in a Fraction (Q) What is a Ordinal Number? - ANSWER Position in a list What is a Cardinal Number? - ANSWER Size of list What is Absolute Error? - ANSWER Difference between actual answer and estimate What is Relative Error? - ANSWER absolute error/true value How does parity bit work? (Odd/Even) - ANSWER Bit (1/0) is added at end of code. Even parity - If there is an even number of 1's, 0 is added Odd parity - If there is an even number of 1's, 1 is added What is Majority Voting? - ANSWER 3 bits are sent that are the same as the original bit, the majority amount received is taken as the original bit. 101 = 1. Good as corrects errors as well as spotting them. What is Check digit? - ANSWER All numbers are added up, then the digits of the answer are added up, this is repeated until you are left with 1 digit. 3+4+2+8 = 17 1+7 = 8 What is Bit/ Colour depth? - ANSWER Amount of bits used to represent all the colours of an image. 17 colours requires 5 bits. What is Metadata? - ANSWER Data about an image/ other data. -Time, Bit depth, Size What is Analogue data? - ANSWER It is infinite and represented in wave form What is Digital data? - ANSWER Represented in binary, finite and can be processed by a computer Why are ADC's used? - ANSWER A computer needs to process analogue signal so data needs to be converted from Analogue to Digital. What is Nyquist's theorem? - ANSWER Sound should be sampled at double the highest frequency. What is Sampling? - ANSWER The process of converting Analogue signals to Digital. -Specific readings of amplitude (Samples) are taken at regular intervals and converted and stored in binary. What happens when sample rate increases? - ANSWER - Increase in file size - Increase in quality What is Encryption? - ANSWER Converting Plaintext to Ciphertext to make it useless for anyone who intercepts it. What is a Caeser Cipher? - ANSWER Moving the alphabet up and down or replacing letters with other letters. What is a Vernam Cipher? - ANSWER Using a randomly generated key for both encryption and decryption. XOR gate is used. What does a Vernam key have to be? - ANSWER - Randomly generated - Same length as plaintext - Only used once - Kept securely What does 'Computationally secure' mean? - ANSWER When data cant be cracked in a reasonable amount of time. Vernam is and Caeser isn't. What is RLE? - ANSWER RLE reduces the size of a file by removing repeated information. It is displayed as, the character of the repeated information followed by the number of times it is repeated. What is Asymmetric and symmetric encryption? - ANSWER Asymmetric - Data is Encrypted using receivers Public Key and Decrypted using Receivers Private Key Symmetric - The same keys are used for Encryption and Decryption. What is Dictionary-Based Compression? - ANSWER Used with data with repeating values. - A library is created with repeating values that are used instead of the original characters to reduce file size What is lossless compression? - ANSWER Data is compressed and can be reconstructed if required as no data is lost. What is Application software? - ANSWER Designed to perform a task. What is Utility software? - ANSWER - Keep computer safe (Encryption, Antivirus) - Maintenance (Data backup) What is Library software? - ANSWER Collections of prewritten code that is used to optimize tasks. What is an Assembler? - ANSWER Converts