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1 . Let $n \geq 5$ be an integer. Consider a uniformly random permutation $a_1a_2 \dots a_n$ of the set $\{1,2,\dots,n\}$. Define the events
A = "$a_1 = 1$",
B = "$a_n = 5$".
What is $\Pr(A \cup B)$?
(a)
None of the above.
(b)
${\frac{2}{n}} - {\frac{1}{n(n-1)}}$
(c)
${\frac{2}{n}} - {\frac{1}{n^{2}}}$
(d)
${\frac{1}{n}} - {\frac{1}{n(n-1)}}$
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