Question

Of the volunteers donating blood in a clinic, 30% have the Rhesus (Rh) factor present in their blood. (a) If five volunteers are randomly selected, what is the probability that at least one does not have the Rh factor

Answer 1

0.83193

Explanation:

Probability of having the Rhesus (Rh) factor present in their blood; p = 0.3

Sample size; n = 5

We want to find the probability the probability that at least one does not have the Rh factor.

This will be;1 - P(X < 1)

This is a binomial probability distribution. Thus;

P(X = k) = C(n, k) × p^(k) × (1 - p)^(n - k)

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

Thus;

P(X = 0) = C(5, 0) × 0.3^(0) × (1 - 0.3)^(5 - 0)

P(X = 0) = 1 × 1 × 0.16807

P(X = 0) = 0.16807

Thus;

1 - P(X < 1) = 1 - 0.16807 = 0.83193