When you look at the table, find the y value that has equivalent values on both sides. For example, the y value for the vertex here is 10. After it, the values are 7,-2, and 17, and above it, the values are 7 and -2. This value should also be either the largest y value or smallest y value (depending on whether the parabola opens up or down).
In probability 2 events are independent if the occurrence of 1 event does not affect the occurrence of the other event. Mathematically, if event A and event B are independent, then
. For our two events in this problem we have that
and
. If these two events are independent, then we should have that,

.A and B are independent events if the probability of A and B is 0.1
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Answer and Explanation:
Given : The random variable x has the following probability distribution.
To find :
a. Is this probability distribution valid? Explain and list the requirements for a valid probability distribution.
b. Calculate the expected value of x.
c. Calculate the variance of x.
d. Calculate the standard deviation of x.
Solution :
First we create the table as per requirements,
x P(x) xP(x) x² x²P(x)
0 0.25 0 0 0
1 0.20 0.20 1 0.20
2 0.15 0.3 4 0.6
3 0.30 0.9 9 2.7
4 0.10 0.4 16 1.6
∑P(x)=1 ∑xP(x)=1.8 ∑x²P(x)=5.1
a) To determine that table shows a probability distribution we add up all five probabilities if the sum is 1 then it is a valid distribution.


Yes it is a probability distribution.
b) The expected value of x is defined as

c) The variance of x is defined as

d) The standard deviation of x is defined as


