Suppose we know that the proportion of a particular populati

Suppose we know that the proportion of a particular population that smokes and is older than 65 is 0.21. If we also know that the proportion of the same population that smokes and is not older than 65 is 0.10, what proportion of this population smokes?

Solution

proportion of population smokes = 0.21 + 0.10 = 0.31