Since all are gone it will be 100%
Answer:



Step-by-step explanation:
Given
Let
A = Event of being a universal donor.
So:


Solving (a): Mean and Standard deviation.
The mean is:



The standard deviation is:




Solving (b): P(x = 3)
The event is a binomial event an dthe probability is calculated as:

So, we have:




The correct answer has to be A