StudyBrixFree worksheets, study guides and courses

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 1 of 5

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

1Algorithms & logicUsing zero-based indexing, what is values[1] for values = [19, 41, 68, 84, 7]?
2Algorithms & logicPython: 17 // 5. What value is returned?
3Algorithms & logicAn outer loop runs 21 times. Each time, an inner loop prints once on each of 22 iterations. How many prints occur?
4Data structuresA sorted array has 31 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 4095 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 63 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 789 MB payload is sent over a constant 40 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 616 MB payload is sent over a constant 165 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 631 MB payload is sent over a constant 85 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 file shrinks from 40 KB to 20 KB. What percentage of its original size was saved?
%
11Digital literacyA raw image is 150 × 28 pixels with 4 bytes per pixel. Ignoring headers and compression, how many bytes?
12Digital literacyAn image is 250 pixels wide and 340 pixels high. How many pixels does it contain?

From Grade 8

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

13Digital literacy (Grade 8)Which device is primarily used to type text into a computer?
14Algorithms & logic (Grade 8)Which instruction represents repetition?
15Digital literacy (Grade 8)A stranger asks for your password in a game chat. What is the safest response?