Official Solution:In a country, 4% of the population owns both a car and a boat. If 20% of boat owners do not have a car, what percentage of the country's population owns a boat? A. 5%
B. 7.5%
C. 10%
D. 12.5%
E. 15%
Let's assume the total population of the country is 100. In this case, the number of people who own both a car and a boat is \(0.04*100 = 4\).
Since 20% of boat owners do not own a car, it follows that 80% of boat owners do own a car, and therefore own both a car and a boat. If we denote the number of people who own a boat as B, then the number of people who own both a car and a boat is 0.8B. We know that there are 4 people who own both a car and a boat, so \(0.8B = 4\). From this, we can calculate that \(B = 5\). This means that 5% of the population owns a boat.
Answer: A