Question

Seven accidents occur in a week. What is the probability that they happen on the same day

• A. $\frac{1}{7^6}$
• B. $\frac{1}{7^7}$
• C. $\frac{1}{7}$
• D. None of these
  

Answer 1

Answer: (A)

$\frac{1}{7^6}$

By product rule, there are seven ways of distributing accidents in span of seven days.
Among those are seven when all accidents
occurred on the same day.
$\therefore P$(seven accidents in week, all .on same day) $=\frac{7}{7^7}=\frac{1}{7^6}$