At a traffic intersection where cars arriving from east can go straight, turn left or turn right. 50% of cars go straight as well as 20% turn left. A current study estimated that 20% of drivers never employ their turn signals while 80% do employ them regularly and proplerly when making turns.

Three independent cars are heading in the intersection from east. All of them don't have a turn signal on. Determine the probability that exactly one of them is going straight.