An easy question on combinations for P1–P2, with a step-by-step solution, diagrams and the answer. Counting arrangements and choices appears in the Hua Xia Cup from the P1 and P2 first rounds to the P5 finals.
The question
Among the school's clubs, 3 meet on Monday, 3 on Wednesday and 2 on Friday, all different.
Ming may join just one.
How many different choices does he have?
Show the hints (2)
💡Hint 1: Just one club: which day could it be on?
💡Hint 2: Any choice of any kind will do. Count them all.
Worked solution
Have a go first, then read the solution step by step.
1.Just one club: it can be any of the 3 on Monday, the 3 on Wednesday or the 2 on Friday.
2.Each one is a choice, so add the three kinds: 3 + 3 + 2 = 8.
⚠️Common mistake: multiplying to get 18. You multiply only when one of each kind must be chosen.
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