Author note — to cover

The probabilities of an exhaustive set of mutually exclusive outcomes total exactly 1; check a stated table, spotting totals over or under 1; tables mixing fractions, decimals and percentages. Both tiers. Exclude solving for unknowns (missing-probabilities page) and exhaustive sets of combined events (Combined events topic). (P4)

• Fluency — direct questions on probabilities that sum to one, limited to this lesson's stated scope (4 questions).
• Application — use the same skill in unfamiliar or contextual questions without introducing a later method (4 questions).
• Check — questions built around the exclusions and likely misconceptions named in the lesson brief (4 questions).