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Question:
2014 Winter Midterm - 15
Author: Michiel Smid
We choose a bitstring of length 25 uniformly at random. What is the probability that this string contains at least two 1s?
(a)
$\sum_{k=2}^{25} {{25}\choose{k}}(1/2)^{k}$
(b)
$1 - (1/2)^{25} - 25(1/2)^{25}$
(c)
$1 + (1/2)^{25} - 25(1/2)^{25}$
(d)
none of the above
COMP 2804: Discrete Structures II
COMP 2804 Midterm