Question

A coin is tossed 3 times. Find the probability of at least two heads.

Solution

Here n = 3
Let p be the probability of getting a head.
$therefore space space space space space straight p space equals space 1 half comma space space straight q space equals space 1 minus straight p space equals space 1 minus 1 half space equals space 1 half$
P(at least 2 heads) = P(2) + P(3)
$equals space straight C presuperscript 3 subscript 2 space open parentheses 1 half close parentheses space open parentheses 1 half close parentheses squared plus space straight C presuperscript 3 subscript 3 space open parentheses 1 half close parentheses cubed space equals space 3 over 1 cross times 1 over 8 plus 1 space cross times 1 over 8 space equals fraction numerator 3 plus 1 over denominator 8 end fraction space equals 4 over 8 equals space 1 half$

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Probability

A coin is tossed 3 times. Find the probability of at least two heads.

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