The probability is \frac{1}{2} that a certain coin will turn up heads on any given toss. If the coin is to be tossed three times, what is the probability that on at least one of the tosses the coin will turn up tails?
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A\frac{1}{8}
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B\frac{1}{2}
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C\frac{3}{4}
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D\frac{7}{8}
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E\frac{15}{16}