Task instructions
Solve efficiently and select the best answer. Show your working in the practice workspace.
Which number is prime?
A. 29
B. 21
C. 27
D. 33
Practice workspace
Write notes or your response
02:00
Reveal answer key / expected response
A — 29
Suggested approach
Translate the statement into mathematical form; compute; check units and reasonableness.
Official-style scoring criteria
Correct result and sound quantitative reasoning.