M E N U DIRECTIONS 1. USEFUL FORMULAS 2. THE CIRCLE (3 VARIATIONS) 3. THE SPHERE (2 VARIATIONS) 4. THE SQUARE (2 VARIATIONS) 5. THE CUBE (2 VARIATIONS) 6. THE RECTANGLE 7. THE AIRPLANE 8. THE SLIDING LADDER 9. MAKING SHADOWS 10. THE CONICAL TANK • 11. THE CONICAL PILE 12. FLYING A KITE 13. REVOLVING SEARCHLIGHT 14. TRAVELING CARS (2 VARIATIONS) 15. MORE SHADOWS 16. THE BASEBALL FIELD 17. THE CYLINDRICAL TANK 18. EQUATION ONE (2 VARIATIONS) 19. EQUATION TWO (2 VARIATIONS) 20. EQUATION THREE (2 VARIATIONS) 21. EQUATION FOUR (2 VARIATIONS) 22. EQUATION FIVE (2 VARIATIONS) 23. EQUATION SIX (2 VARIATIONS) 24. EQUATION SEVEN 25. THE REVOLVING BEACON 26. THE ISOSCELES TROUGH 27. THE SPACE SHUTTLE 28. GONE FISHING 29. THE CLOCK 30. THE TRIANGLE #1 31. THE TRIANGLE #2 32. THE SNOWBALL 33. THE OTHER AIRPLANE 34. YET ANOTHER SHADOW 35. THE BASKETBALL SHADOW 36. MAKING COFFEE

THE CONICAL GRAVEL PILE PROBLEM At a sand and gravel plant, gravel is falling off a conveyor and into a conical pile at a rate of 14 feet3/minute. The diameter of the base of the cone is approximately 4 times the altitude. When the pile is 9 feet high, determine the following: (A) At what rate is the height is the pile changing? (B) At what rate is the radius of the pile changing?