If a fair coin is tossed three times what is the probability that heads shows once and tails shows twice?
I thought the answer would be $1/4 + 1/2$ because the probability of getting heads is $1/2$ and the probability of getting tails twice is $1/2 * 1/2 = 1/4,$ but this is incorrect. I am not sure what I did wrong.
Best Answer
This can happen in $\dbinom{3}{1}$ ways. Therefore probability $= 3 \times \dfrac{1}{2} \times \dfrac{1}{2}\times \dfrac{1}{2}$