[size=150]For Problem Type 1, choose the correct answer choice from the drop down menu. [br]When you have chosen the correct answer, it will turn green.[br]For Problem Type 2, find the correct value for r and type it into the box then press enter.[br]If your answer is correct, it will turn green.[br]Click "New Problem" to see another example problem of the same type.[br]Click "Switch Problem Types" to move between the two types of problems.[/size]