Question

Find the mean, variance and standard deviation for the probability distribution given below:

X: -5, 2, 12, 8,

P(X): 0.575, 0.142, 0.209, 0.074

A. Mean =

B. Variance =

C. Standard Deviation =

Answer 1

Solution :

x	P(x)	x * P(x)	x2 * P(x)
-5	0.575	-2.875	14.375
2	0.142	0.284	0.568
12	0.209	2.508	30.096
8	0.074	0.592	4.736
Sum	1	0.509	49.775

A) Mean = = X * P(X) = 0.509

B)

Variance

= X ² * P(X) - ²

= 49.775 - 0.509²

= 49.51592

C)

Standard Deviation = Variance = 7.036755