Question

The following function is probability mass function.

F(x) = 6x+4/80, x = 0,1,2,3,4

Determine the mean, ?, and variance, ?2, of the random variable.

Round your answers to two decimal places (e.g. 98.76).

? =

?2 =

Answer 1

2.75

1.4375

Explanation:

From the pdf given for a discrete variable x, we substitute for x and get probability as follows

x 0 1 2 3 4

F(x) 0.05 0.125 0.2 0.275 0.35 1

x*F 0 0.125 0.4 0.825 1.4 2.75

x^2*F 0 0.125 0.8 2.475 5.6 9

Mean of x = 2.75

Var(x) = E(x square)-2.75 square

=
`9-2.75^2\\\\=1.4375`