Seven (distinct) car accidents occurred in a week. What is the probability…
2001
Seven (distinct) car accidents occurred in a week. What is the probability that they all occurred on the same day?
- A.
1/7^7
- B.
1/7^6
- C.
1/2^7
- D.
7/2^7
Attempted by 4 students.
Show answer & explanation
Correct answer: B
Each of the 7 distinct accidents can occur on any one of the 7 days of the week.
Total possible day assignments = 7^7.
For all accidents to occur on the same day, choose that common day in 7 ways: all on Monday, all on Tuesday, and so on.
Favourable outcomes = 7.
Therefore, probability = 7 / 7^7 = 1 / 7^6. Hence, option B is correct.