Question: A certain radioactive substance has a half-life of 23 years. For how long must the substance decay so that there is 18% of the original amount remaining? For full credit you must solve an appropriate equation.
Question: A farmer uses 1200 feet of fence to enclose a rectangular region and also to subdivide the region into three smaller rectangular regions by placing fences parallel to one of the sides. Find the dimensions that produce the greatest enclosed area.