Answer:
The probability is 0.0428
Step-by-step explanation:
First, let's remember that the binomial distribution is given by the formula:
where k is the number of successes in n trials and p is the probability of success.
However, the problem tells us that when there isn't a number of trials fixed, we can use the geometric distribution and the formula for getting the first success on the xth trial becomes:

The problem asks us to find the probability of the first success on the 4th trial (given that the first subject to be a universal blood donor will be the fourth person selected)
Using this formula with the parameters given, we have:
p = 0.05
x = 4
Substituting these parameters in the formula and solving it, we get:

Therefore, the probability that the first subject to be a universal blood donor is the fourth person selected is 0.0428 or 4.28%
Answer:
337.5
Step-by-step explanation:
4 1/2*5*3 3/4
Both 15 and 20 can be divided evenly by 5, so 5 is the greatest common monomial: 5(3x^2 + 4x) or 5x(3x + 4)
X= 10
This is because 180-95= 85 which would make 8x+5= 85
Subtract 5 from both sides and get 8x=80
Then, divide 8 from both sides and get x=10