A person who has a heart attack can be saved 90% of the time if a defibrillator is used within 5 minutes of the heart attack. Of the people that have heart attacks, defibrillators are within the vicinity 40% of the time; however, they are only used 60% of the time even when they are in the surrounding area. How many people who suffer a heart attack are saved because of the use of a defibrillator?