The number of electrical outages in a city has the following

The number of electrical outages in a city has the following probability distribution: x-f(x) 0-10% 1-20% 2-30% 3-40%, What are the mean and standard deviation for the number of outages?

Solution

the following probability distribution:

x-f(x)

0-10% --- 0.1

1-20% ----0.2

2-30% ----0.3

3-40%,----0.4

mean and standard deviation for the number of outage

Mean = (0.1+0.2+0.3+0.4)/4 = 0.25

standard deviation =sqrt((0^2 * 0.1) + (1^2 * 0.2) + (2^2 * 0.3) + (3^2 * 0.4) - 2^2) =sqrt (1)=1