Question

In a group of 10 people, there are 4 people that have the flu virus. Suppose we pick 3 random persons to test in order to determine if they have the flu and, to simplify our analysis, we suppose that the test is 100% accurate. Let X be the random variable consisting of the number of positive flu tests out of 3.

Answer 1

Tests is 100% Accurate, so by using the formula of random variable probability.

Explanation:

Total number of people = 10

Sample space = p(A) = 10

Number of people that have flu = n(s) = 4

Pick random 3 persons, the possibility that they have flue is n(A) = ?

Let X is the random variable, consisting of number of positive flu test,

Tests is 100% Accurate, so by using the formula of random variable probability, we get

P(X) = n (A) / n(S)

P(X) = ¾, is the probability of having positive flu test