Computer Studies Questions and Answers - Form 3 Mid Term 2 Exams 2023

QUESTIONS

1. Define the term data integrity. (2mks)
2. State three ways of minimizing threats to data integrity. (3mks)
3.  
   1. Subtract 110₂ from 11010(2mks)
   2. Find the sum of binary number 101.101₂ and 110.100₂ (3mks)
   3. Convert binary number 11010110.1001₂ into octal number. (3mks)
   4. Convert binary number 11010110.1001₂ into hexadecimal number. (3mks)
4. Convert the following numbers to their decimal equivalent. (6mks)
   1. 0.11011₂
   2. 11.011₂
5. Convert 3BD₁₆ to Octal. (3mks)
6. using one’s complement, calculate 5₁₀ – 9₁₀ . Use six bit in your calculation. (3mks
7. State at least four advantages of storing data in computer files over the manual filing system (3mks)
8. With aid of a diagram highlight four main stages of data processing. (6mks)
9. Discuss five stages of data collection (10mks)
10. Define the following elements of a computer file. (3mks)
    1. Character
    2. Field
    3. Record

MARKING SCHEME

1. Define the term data integrity. (2mks)
   • Data integrity refers to the dependability, timeliness, availability, relevance, accuracy & completeness of data/information
2. State three ways of minimizing threats to data integrity. (3mks)
   • Backing up the data on external storage media
   • Enforcing security measures to control access to data
   • Using error detection & correction software  when transmitting data
   • Designing user interfaces that minimize chances of invalid data being entered
3.  
   1. Subtract 110₂ from 11010₂                (1mk)
      11010₂
          110₂
      10100₂
   2. Find the sum of binary number 101.101₂ and 110.100₂ (1mk)
      101.101₂
      110.100₂ 
      1100.001₂
   3. Convert binary number 11010110.1001₂into octal number. (1mk)
      
   4. Convert binary number 11010110.1001₂ into hexadecimal number. (1 mark)
      
4. Convert the following numbers to their decimal equivalent
   1. 1. 11.011₂                        (2 marks)
         (2⁰ x 1) + (2¹ x 1) + (2 ⁻¹ x 0) + (2^-2 x 1) + (2^-3 x 1)
         = 1 + 2  +0 + 0.25 + 0.125
         = 3.375₁₀
      2. 0.11011₂ (2 marks)
         0. (2^-1 x 1) + (2^-2 x 1) + (2^-3 x 0)+ (2^-4 x 1) + (2^-5 x 1)
         0. 5 + 0.25+ 0.0 + 0.0625 + 0.03125
         = 0.84375₁₀
5. Convert 3BD16 to Octal. (3mks)
   A = 10 = 1010
   B = 11 = 1011
   C = 12 = 1100
   D = 13 = 1101 1mk
   001 l 010 l 101 l 110 l 001 l 101
      1      2       5       7      1      5 ✔1mk
   Therefore ABCD₁₆ = 125715₈               ✔1mk
6. Using one’s complement, calculate 5₁₀ – 9₁₀. use six bit in your calculation. (3mks)
   Conversion
   510 = 000101₂
   910 = 001001₂  ✔1mk
   -910: ones complement = 110110
   Adding 000101   ✔1mk
   110110 +
   111011₂     ✔1mk
7. State at least four advantages of storing data in computer files over the manual filing system (4mks)
   • Stored information takes up less space
   • Easier to update and modify
   • Provides faster access and retrieval of data
   • Reduces duplication of data or stored records
   • Cheaper 
   • Enhances data integrity (i.e. accuracy and completeness)
8. With aid of a diagram highlight four main stages of data processing. (6mks)
   
9. Discus five stages of data collection (10mks)
   • Data creation
   • Data preparation
   • Conversion
   • Validation
   • transmission
10. Define the following elements of a computer file. (3mks)
    1. Character
       • a character is the smallest element in a computer file and refers to a letter, number or special symbol that can be input, processed stored and output by a computer.
    2. Field
       • a field is a logical combination of characters to represents meaningful piece of data.
    3. Record
       • a record is a collection of related fields that represent a single entity.