**Question: **Farmer Brown has 80 feet of fence with which he plans to enclose 3 identical rectangular pens along the side of a barn. What are the dimensions of the pen to maximize the enclosed area?

## Calculus: General Differentiation – #29248

**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 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.