Page 44 - Math SL HB Sem 3
P. 44
Watch Out:
Always check if the answer makes sense:
Probability cannot be negative nor greater than I (i.e. 0 < P1 S 1) However, for expectation,
t(X), no such limitations apply.
Example:
The following table shows the probability distribution of a discrete random variable x
x 5 3 7
P(x x) 0;7925 3uz 4u
=
a) Find the value of u.
b) Find the expected value of x.
\. Example:
The probability distribution for a random variable X is given by
i
p(X=x)= 2x+1
15
wherex = 0, 1,5.
a) Calculate P(X = 5).
r b) Verify that this probability distribution is valid.
c) Find p(X < 5).
d) Find E (x).
2
