Probability distribution. Toss a coin twice, write down the observed number of heads and their associated probabilities. Find the mean and standard deviation of the distribution. Solution num of heads 0 1 2 probability 1/4 1/2 1/4 mean = 1*1/2 + 2*1/4 = 0.5 + 0.5 =1 st. dev = sqrt( (1-1/2)2 + (2*1/4 - 1)2) = 1/2.

1. Probability distribution. Toss a coin twice, write down the observed number of heads and their
associated probabilities. Find the mean and standard deviation of the distribution.
Solution
num of heads 0 1 2
probability 1/4 1/2 1/4
mean = 1*1/2 + 2*1/4 = 0.5 + 0.5 =1
st. dev = sqrt( (1-1/2)2 + (2*1/4 - 1)2)
= 1/2