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Probablity

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Probablity

by ketkoag » Mon Mar 30, 2009 8:23 am
A coin that is tossed will land heads or tails, and each outcome has equal probability. What is the
probability that the coin will land heads at least once on two tosses?
A. 1/4
B. 1/3
C. 1/2
D. 2/3
E. 3/4

I selected the right answer that is E.
I've calculated it by 1/4 + 1/4 + 1/4 i.e. (H,T)(H,H)(T,H)
or we can calculate it by 1- prob. of not having head.

please lemme know whether i am correct.
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by moutar » Mon Mar 30, 2009 8:28 am
I would say you are spot on.
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by mike22629 » Mon Mar 30, 2009 9:38 am
another way to do this problem is the 1-x probability. Find the probability of it landing tails twice.

(1/2)(1/2) = 1/4

Subtract that from 1

1 - (1/4) = 3/4
Probability of it landing heads at least once.
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by mike22629 » Mon Mar 30, 2009 9:38 am
oops just realized you already suggested that.
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