Respuesta :
Answer:
a) x 0 1 2
P(X=x) 0.2 0.5 0.3
b) CDF attached as an image
Step-by-step explanation:
a) Let us denote probability of threat in system 1 with P(T1) and probability of threat in system 2 with P(T2).
P(T1) = 0.6
P(T2) = 0.5
The probability that there is no threat in system 1 is:
P(T1)' = 1 - P(T1)
= 1 - 0.6
P(T1)' = 0.4
Similarly,
P(T2)' = 1 - P(T2)
= 1 - 0.5
P(T2)' = 0.5
The sample points for this situation can be:
(T1,T2) (T1',T2) (T1,T2') (T1',T2')
X = number of systems in which threats were detected. i.e. 0,1,2
P(X=0) = P(T1',T2')
= P(T1)' * P(T2)'
= 0.4 * 0.5
P(X=0) = 0.2
P(X=1) = P(T1,T2') + P(T1',T2)
= P(T1) * P(T2)' + P(T1)' * P(T2)
= 0.6*0.5 + 0.4*0.5
=0.3 + 0.2
P(X=1) = 0.5
P(X=2) = P(T1,T2)
= P(T1) * P(T2)
= 0.6*0.5
P(X=2) = 0.3
PMF of X:
x 0 1 2
P(X=x) 0.2 0.5 0.3
b) The cumulative distribution function can be plotted by adding up the probabilities of each point with that of its previous points. i.e.
P(X≤0) = P(X=0) = 0.2
P(X≤1) = P(X=0) + P(X=1) = 0.2 + 0.5 = 0.7
P(X≤2) = P(X=0) + P(X=1) + P(X=2)
= 0.2 + 0.5 + 0.3
P(X≤2) = 1
Now we need to plot this CDF. On the x-axis, we will plot the values of X and on the y-axis, we will plot the values of CDF. I am attaching the plot as an image.
