ITPEC FE Subject A April 2024 Question 2
ITPEC FE Subject A April 2024 — Question 2 of 60
Probability with identical items — find the chance all 5 people get the correct drink type.
Two people ordered coffee, three ordered tea. Drinks of the same type are identical.
- •Total ways to distribute: choose 2 of 5 to get coffee →
C(5,2) = 10 - •Favorable outcomes: exactly
1(the two coffee-orderers get coffee) - •Probability =
1 / 10
Why not others:
- (a) 1/30 — incorrect combinatorial count
- (b) 1/20 — incorrect combinatorial count
- (d) 3/10 — confuses "all correct" with "at least one correct"
Key rule: When items are identical within groups, use combinations C(n, k) to count arrangements, not permutations.
AI-generated — may contain errors
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