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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 5 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 18 times. Each time, an inner loop prints once on each of 8 iterations. How many prints occur?
2Algorithms & logicUsing zero-based indexing, what is values[0] for values = [56, 70, 31, 55, 75]?
3Algorithms & logicFOR i FROM 1 TO 76 INCLUSIVE STEP 3: print i. How many numbers are printed?
4Data structuresA sorted array has 2047 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 7 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 15 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 712 MB payload is sent over a constant 200 Mbps link. Use decimal MB and ignore overhead. Find transfer time. Round the final result to 4 decimal places if needed. Answer in s.
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8Data systemsA 829 MB payload is sent over a constant 70 Mbps link. Use decimal MB and ignore overhead. Find transfer time. Round the final result to 4 decimal places if needed. Answer in s.
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9Data systemsA 436 MB payload is sent over a constant 135 Mbps link. Use decimal MB and ignore overhead. Find transfer time. Round the final result to 4 decimal places if needed. Answer in s.
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10Digital literacyHow many bits are in 8007 bytes?
11Digital literacyA raw image is 138 × 185 pixels with 4 bytes per pixel. Ignoring headers and compression, how many bytes?
12Digital literacyAn image is 170 pixels wide and 390 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)What is an algorithm?
15Digital literacy (Grade 8)A stranger asks for your password in a game chat. What is the safest response?