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Grade 9 · Computer science

Grade 9 Computer science diagnostic

15 questions on algorithms & logic, digital literacy, data systems and data structures, plus 3 from Grade 8. Answer what you can, then check your answers to see which topics are secure and what to practise next.

15 questions4 topicsAbout 15 minutesSet 2 of 5

Skip a question if you do not know the answer. It is better than guessing, because it shows what to practise.

1Algorithms & logicAn outer loop runs 20 times. Each time, an inner loop prints once on each of 6 iterations. How many prints occur?
2Algorithms & logicConvert the binary number 1001000101 to decimal.
3Algorithms & logicStart with total = 46. Repeat 23 times: add 12 to total. What is the final total?
4Data structuresA sorted array has 8191 entries. Binary search always inspects a middle entry. What is the largest number of inspected entries for a successful search? Round the final result to 4 decimal places if needed.
5Data structuresA sorted array has 524287 entries. Binary search always inspects a middle entry. What is the largest number of inspected entries for a successful search? Round the final result to 4 decimal places if needed.
6Data structuresA sorted array has 32767 entries. Binary search always inspects a middle entry. What is the largest number of inspected entries for a successful search? Round the final result to 4 decimal places if needed.
7Data systemsA 668 MB payload is sent over a constant 190 Mbps link. Use decimal MB and ignore overhead. Find transfer time. Round the final result to 4 decimal places if needed. Answer in s.
s
8Data systemsA 293 MB payload is sent over a constant 25 Mbps link. Use decimal MB and ignore overhead. Find transfer time. Round the final result to 4 decimal places if needed. Answer in s.
s
9Data systemsA 852 MB payload is sent over a constant 25 Mbps link. Use decimal MB and ignore overhead. Find transfer time. Round the final result to 4 decimal places if needed. Answer in s.
s
10Digital literacyA raw image is 144 × 11 pixels with 3 bytes per pixel. Ignoring headers and compression, how many bytes?
11Digital literacyAn image is 190 pixels wide and 320 pixels high. How many pixels does it contain?
12Digital literacyA file shrinks from 1240 KB to 496 KB. What percentage of its original size was saved?
%

From Grade 8

These questions check skills from the grade below, so gaps can be spotted early.

13Algorithms & logic (Grade 8)Which instruction represents repetition?
14Digital literacy (Grade 8)Which device is primarily used to type text into a computer?
15Algorithms & logic (Grade 8)What is an algorithm?