Answer:
The probability that the first subject to be a universal blood donor is the seventh person selected is 0.0511
Step-by-step explanation:
Let's start defining the random variable X.
X : ''The first success is on the xth trial''
X can be modeled as a geometric random variable with the following probability function :
Where is the probability of the random variable X to assumes the value ''x''.
The variable p is the success probability.
For this exercise, we define a success as someone randomly selected is a universal donor and that probability is
We are looking for :
The probability function is :