Question

If a patient is waiting for a suitable blood donor and the probability that the selected donor will be a match is 0.2 , then find the expected number of donors who will be tested till a match is found including the matched donor.

a. 5
b. 2
c. 0.2
d. 4

Answer 1

Answer: a

Step-by-step explanation: To find the expected number of donors who will be tested till a match is found, we can use the concept of geometric distribution.

The expected number of trials until the first success in a series of Bernoulli trials with probability of success p is given by 1/p.

In this case, the probability of finding a match is 0.2, so the expected number of donors who will be tested till a match is found is:

1 / 0.2 = 5

Therefore, the expected number of donors who will be tested till a match is found, including the matched donor, is 5. So, the answer is option a. 5.