A fair coin is tossed 5 times. What is the probability that it lands heads up at least twice? Choose the correct choice from the following answers.
A) 1/16	B) 5/16	C) 2/5	D) 13/16	E) 27/32
Fair coin is tossed 5 times . Hence total number of outcomes = 2^5 = 32.   Problem asks for probability of getting atleast heads twice. Hence if we calculate probability of getting Heads exactly once and probability of not getting Heads at all and subract it from the total probability of the event which is 1 (As total probability of certain event will be always 1) we can get the probability of getting atleast heads twice.   Probability of getting exactly one head and no heads= (Number of possible outcomes [ HTTTT , THTTT, TTHTT, TTTHT, TTTTH , TTTTT] = 6)/ (Total possible outcomes = 32)   =&gt; 6/32 = 3/16   Hence probability of getting atleast heads twice = 1 - (3/16) = 13/16 =&gt; Choice [13/16]
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A fair coin is tossed 5 times. What is the probability that it lands heads up at least twice?