Computers store and manipulate data - Edexcel - GCSE Computer Science - Question 4 - 2021 - Paper 1

To convert the binary number 1010 1101 to hexadecimal, group the binary digits into sets of four from right to left:

1010 1101

The leftmost group can be converted directly:

• 1010 in binary is A in hexadecimal.
• 1101 in binary is D in hexadecimal.

Thus, the binary number 1010 1101 corresponds to the hexadecimal number AD.

To convert the hexadecimal number E3 to binary:

• 'E' in hexadecimal is 1110 in binary.
• '3' in hexadecimal is 0011 in binary.

So, E3 in hexadecimal is:

1110 0011

Now, to convert 1110 0011 to denary: $1 imes 2^7 + 1 imes 2^6 + 1 imes 2^5 + 0 imes 2^4 + 0 imes 2^3 + 1 imes 2^2 + 1 imes 2^1 + 1 imes 2^0$ This calculates to: $128 + 64 + 32 + 0 + 0 + 4 + 2 + 1 = 227$

Thus, E3 in hexadecimal is equivalent to 227 in denary.

The ASCII code for the character 'E' is 69 in denary.

To convert this to 8-bit binary, we convert 69 to binary:

• 69 in binary is:

01000101

Thus, the ASCII code for 'E' in 8-bit binary is 01000101.

When comparing 8 bits and 24 bits used to represent sound, we can consider the following effects:

• Effect on Sample Resolution: With 24 bits, there are more levels of amplitude that can be represented, resulting in finer detail in sound quality.

• Effect on Accuracy of Representation: The sound reproduces more accurately to the original with 24 bits.

• Effect on Transmission Speed/Storage: 24 bits takes longer to transmit and creates larger file sizes, using more memory compared to 8 bits.

To complete the table for the addition of the binary numbers:

        0 0 1 1 1 0 1 0
  +     1 0 1 1 0 0 1 1
---------------------
        1 0 0 1 0 0 0 1

The result of the addition is 10010001.

Changing the most significant bit (MSB) of the first binary number affects the result as the MSB represents the highest value in binary. This change can lead to an increase in the total value, possibly changing the result of the addition as the MSB now contributes more significantly to the sum.