SOLUTION: Please help me solve the following question. The random variable X has the following distribution. x = -1, 9, 1, 2 P(X=x) 3c, 2c, 0.4, 0.1 Find the variance and standard de

Question 1081927: Please help me solve the following question.
The random variable X has the following distribution.
x = -1, 9, 1, 2
P(X=x) 3c, 2c, 0.4, 0.1
Find the variance and standard deviation.
Answer by Boreal(15235) (Show Source): You can put this solution on YOUR website!
The value of c can be determined. We know that 3c+2c=0.5 and 5c=0.5, so c=0.1 and the probability of x=-1 is 0.3, x=9 is 0.2, x=1 is 0.4 and x=2 is 0.1
E(X)=-0.3+1.8+0.4+0.2=2.1
V(X)=(x-E(X))^2*p(x)
-3.1^2*0.3=2.883
6.9^2*0.2=9.522
1.1^2*0.4=4.84
0.1^2*0.1=0.001
They add to 17.246
sd is sqrt (V)=4.153
RELATED QUESTIONS
Please help me solve probability question. The random variable X has the following... (answered by Boreal)

Please help me solve this problem..I will appreciate your help.

The random... (answered by Edwin McCravy,natolino_2017)
A random variable X has the following probability function define as P(X=x) = {2c, 3c,... (answered by robertb)
A random variable x has the following probability mass function defined in tabular form... (answered by math_tutor2020)
Q1 
Suppose that the random variable X has the following cumulative distribution... (answered by robertb)
Q1 
Suppose that the random variable X has the following cumulative distribution... (answered by Fombitz)
1.	A fair coin is thrown in the air four times. If the coin lands with the head up on the  (answered by stanbon)
a random variable X  has the following probability distribution.

x|1|2|3|4|5|... (answered by ewatrrr)
 A random variable X has the following probability distribution:
X	P(X)
-2	0.1
-1	k
0	 (answered by htmentor)