Answer:
F(x) = 0 ; x < 0
0.064 ; 0 ≤ x < 1
0.352 ; 1 ≤ x < 2
0.784 ; 2 ≤ x < 3
1 ; x ≥ 3
Explanation:
Each wafer is classified as pass or fail.
The wafers are independent.
Then, we can modelate X : ''Number of wafers that pass the test'' as a Binomial random variable.
X ~ Bi(n,p)
Where n = 3 and p = 0.6 is the success probability
The probatility function is given by :
Where is the combinatorial number
Let's calculate f(x) :
For the cumulative distribution function that we are looking for :
The cumulative distribution function for X is :
F(x) = 0 ; x < 0
0.064 ; 0 ≤ x < 1
0.352 ; 1 ≤ x < 2
0.784 ; 2 ≤ x < 3
1 ; x ≥ 3