00:01
We are told that the average unemployment rate in california in august of 2020 was 11 .4%.
00:06
We pick 400 employable people in california at that point.
00:12
So the probability of each of these people being unemployed is 11 .4%, not 0 .114.
00:20
Notice i have switched to decimal form here because percentages don't play well with calculations.
00:25
We want the expected value for the number of people in the sample who were unemployed.
00:31
So the first step is to recognize this is a binomial distribution.
00:36
A random sample, so we have n independent trials, two outcomes for each, they are unemployed or otherwise, same probability p for each of them.
00:46
So it's a binomial and the expected value or mean of a binomial is equal to np.
00:52
So if we multiply these we get 45 .6.
00:57
Intuitively you'd think okay 11 .4 % of people in california at this point were unemployed, therefore i expect 11 .4 % of my sample to be unemployed.
01:07
So this is the expected value...