Fifteen football players of a club are given T-shirts with their names written on the back. If the players pick up the T-shirts randomly, then the probability that at least players pick the correct T-shirt is:
- A
- B
- C
- D
Fifteen football players of a club are given T-shirts with their names written on the back. If the players pick up the T-shirts randomly, then the probability that at least players pick the correct T-shirt is:
Correct answer:A
Standard Method
Given: There are players and named T-shirts, and each player picks one T-shirt at random.
Find: The probability that at least players pick the correct T-shirt.
The solution states that the correct option is A. It also presents the setup
which corresponds to subtracting the cases with exactly , , or correct picks.
Using the derangement notation shown in the solution,
so the displayed expression becomes
the solution then simplifies this approximately and reaches a numerical discussion, but its written intermediate approximation is inconsistent with its own final marked option.
Since the solution explicitly declares Option A as correct, the answer is taken as A, which is
Therefore, the correct option is A.
Discrepancy Noted from the solution
Given: The source the solution marks Option A as correct.
Find: The final answer to be recorded.
The solution contains a contradiction:
Because the page explicitly labels the correct option as A, and the worked approximation is internally inconsistent, the safest grounded extraction is to record the answer as A and preserve the discrepancy in the solution notes.
Therefore, the extracted correct answer is , i.e. Option A.
Students may count permutations with at least correct picks directly. That becomes cumbersome and error-prone. Instead, count the complement: exactly , , and correct picks, then subtract from .
A common mistake is to use ordinary permutations instead of derangements for the remaining players. After fixing some correct picks, the others must all be incorrect, so derangement counts such as or are required.
Students may trust a contradictory final numeric line without checking consistency. Here the solution itself contains inconsistent approximation statements, so the explicitly marked correct option must be used carefully.
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