6 exam-style questions with full mark schemes and model answers. Write your own answer and the AI examiner marks it against the mark scheme.
Learn this properly: Number Systems: Binary and Denary (Decimal)A computer stores images as bitmaps. An app uses lossless compression for diagrams and lossy compression for photographs.
Explain the difference between lossy and lossless compression, and discuss why the app uses lossless compression for diagrams but lossy compression for photographs. You should refer to file size and quality in your answer. (6 marks)
All numbers below are 8-bit unsigned binary.
(a) Add the two binary numbers 01101101 and 01010110. Show your working (including any carries) and give the 8-bit result. (2 marks)
(b) State what is meant by overflow, and explain whether overflow occurs in your addition in part (a). (2 marks)
Answer the following conversions. Show your working.
(a) Convert the denary number 214 to 8-bit binary. (1 mark)
(b) Convert the binary number 10110100 to hexadecimal. (1 mark)
(c) Convert the hexadecimal number 2F to denary. (1 mark)
A sound engineer records a short audio clip. The recording uses a sample rate of 44 100 Hz, a bit depth of 16 bits, and lasts 30 seconds. (The recording is in mono — a single channel.)
Calculate the size of the uncompressed sound file. Use size (bits)=sample rate×bit depth×duration. Give your answer in bits and then in kilobytes (KB), taking 1 KB=1000 bytes. (3 marks)
A character set such as ASCII is used to represent text in a computer.
(a) State what is meant by a character set. (1 mark)
(b) Standard ASCII uses 7 bits per character. State how many different characters standard ASCII can represent, and show how you worked it out. (1 mark)
State how many bits there are in one byte. (1 mark)