In a certain population, 99% of the people have Rh-positive blood. Suppose that two people from this population marry. What is the probability that they are both Rh-negative, thus making it inevitable that their children will be Rh-negative?

The probability that both will be Rh-negative out of 99% Rh-positive is 0.01 x 0.01 = 0.0001.

Explanation:

The population contain 99℅ of Rh-positive. This represent almost all of the people.

However, there is still 1℅ chance of having an individual of Rh-negative.

Both of them will have the probability of 1℅ of having Rh-negative(0.01).

Therefore, Pr(Rh-negative AND Rh-negative) = 0.01 x 0.01. The result is approximately equals zero.

The both parents having Rh-negative, will have a dominant Rh-negative blood passed to their children, only recessive Rh-positive of 25℅ chance.

Since the chance of Rh-negative blood passed to their children is 75℅, it is inevitable that their children will be Rh-negative

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