Suppose the probability of contracting a certain disease is 1 in 27,124 for a new case in a given year. Approximate the probability that in a town of 5,756 people there will be at least one new case of the disease next year.

Respuesta :

Answer:

The probability that there is at least one new case of the disease is approximately 0.19121

Step-by-step explanation:

Given that the probability of contracting a disease is p = 1/27124.

In an experiment n = 5756, we want to find the probability that there will be at least one new case of the disease. That is P(X ≥ 1).

If x is approximated Binomial(n, p)

Then

P(X = x) = (nCx)(p^x)q^(n - x)

Where q = 1 - p

Here, q = 1 - (1/27124) = 27123/27124

And nCx, read as "n combination x"

is given as n!/(n - x)! x!

Also note that

P(X ≥ a) = 1 - P(X < a)

So, it is sufficient to find P(X < 1) for this problem.

P(X < 1) = P(X = 0)

= (5756C0)(1/27124)^0(27123/27124)^(5756 - 0)

= 1 × 1 × 0.80879

≈ 0.80879

Now,

P(X ≥ 1) = 1 - 0.80879 = 0.19121